I created a script that searched through the files of SMF (2 for right now) that grabs all of the keys from variables. It only works for $var['{KEY}']. I should come up with a better way to document it.
allow_disableAnnounce 0 => Post.php 1 => Profile.template.php
allow_editDisplayName 0 => Profile.php 1 => Register.php
allow_guestAccess 0 => LogInOut.php 1 => index.php
allow_hideOnline 0 => Profile.php
allow_hide_email 0 => Display.php 1 => Groups.php 2 => Load.php 3 => Memberlist.php 4 => News.php 5 => PersonalMessage.php 6 => Profile.php 7 => Register.php 8 => Search.php 9 => Subs-Auth.php 10 => Subs-Members.php
allow_ignore_boards 0 => Load.php 1 => Profile.php
allow_sm_stats 0 => Stats.php
approveAccountDeletion 0 => Profile.php
attachmentCheckExtensions 0 => Post.php 1 => Subs-Post.php 2 => Post.template.php
attachmentDirSizeLimit 0 => ManageAttachments.php 1 => Post.php 2 => Subs-Post.php
attachmentEnable 0 => Display.php 1 => Post.php
attachmentEncryptFilenames 0 => Subs-Post.php 1 => Subs.php
attachmentExtensions 0 => Post.php 1 => Subs-Post.php
attachmentNumPerPostLimit 0 => Post.php 1 => Post.template.php
attachmentPostLimit 0 => Post.php
attachmentShowImages 0 => Display.php
attachmentSizeLimit 0 => Post.php 1 => Subs-Post.php 2 => Post.template.php
attachmentThumbHeight 0 => Display.php 1 => Subs-Post.php
attachmentThumbWidth 0 => Display.php 1 => Subs-Post.php
attachmentThumbnails 0 => Display.php 1 => Subs-Post.php
attachmentUploadDir 0 => Display.php 1 => ManageAttachments.php 2 => Post.php 3 => Profile.php 4 => Subs-Graphics.php 5 => Subs-Package.php 6 => Subs-Post.php 7 => Subs.php
autoFixDatabase 0 => Database.php 1 => Subs-Db-mysql.php 2 => Subs-Db-postgresql.php 3 => Subs-Db-sqlite.php
autoLinkUrls 0 => Subs.php
autoOptMaxOnline 0 => ScheduledTasks.php
avatar_action_too_large 0 => Load.php 1 => Profile.php 2 => Subs.php
avatar_directory 0 => ManageAttachments.php 1 => Profile.php 2 => Subs-Package.php
avatar_download_external 0 => Profile.php
avatar_download_png 0 => Subs-Graphics.php
avatar_max_height_external 0 => Load.php 1 => Profile.php 2 => Subs.php 3 => Profile.template.php
avatar_max_height_upload 0 => Profile.php
avatar_max_width_external 0 => Load.php 1 => Profile.php 2 => Subs.php 3 => Profile.template.php
avatar_max_width_upload 0 => Profile.php
avatar_resize_upload 0 => Profile.php
avatar_url 0 => Load.php 1 => Profile.php 2 => Subs.php 3 => Profile.template.php
banLastUpdated 0 => Security.php
bbc_disabled_disabledBBC 0 => ManagePosts.php
bbc_disabled_signature_bbc 0 => ModSettings.php
cache_enable 0 => Database.php 1 => Load.php 2 => MoveTopic.php 3 => News.php 4 => Search.php 5 => Subs-Auth.php 6 => Subs-Db-mysql.php 7 => Subs-Db-postgresql.php 8 => Subs-Db-sqlite.php 9 => Subs.php
cache_memcached 0 => Load.php
cal_allow_unlinked 0 => Calendar.php
cal_allowspan 0 => Calendar.php 1 => Post.php 2 => Subs-Calendar.php 3 => Post.template.php 4 => Calendar.template.php
cal_days_for_index 0 => SSI.php 1 => BoardIndex.php
cal_daysaslink 0 => Calendar.template.php
cal_defaultboard 0 => Calendar.php 1 => Post.php
cal_enabled 0 => BoardIndex.php 1 => Calendar.php 2 => Display.php 3 => ManageCalendar.php 4 => Subs.php
cal_maxspan 0 => Calendar.php 1 => Post.php 2 => Subs-Calendar.php 3 => Post.template.php 4 => Calendar.template.php
cal_maxyear 0 => Calendar.php 1 => Post.php 2 => Subs-Calendar.php 3 => Post.template.php 4 => Calendar.template.php 5 => ManageCalendar.template.php
cal_minyear 0 => Calendar.php 1 => Post.php 2 => Subs-Calendar.php 3 => Post.template.php 4 => Calendar.template.php 5 => ManageCalendar.template.php
cal_showInTopic 0 => Display.php
cal_showbdays 0 => BoardIndex.php 1 => Calendar.php
cal_showevents 0 => BoardIndex.php 1 => Calendar.php
cal_showholidays 0 => BoardIndex.php 1 => Calendar.php
cal_showweeknum 0 => Calendar.php
censorIgnoreCase 0 => Load.php 1 => Admin.template.php
censorWholeWord 0 => Load.php 1 => Admin.template.php
censor_proper 0 => Load.php 1 => ManagePosts.php
censor_vulgar 0 => Load.php 1 => ManagePosts.php
compactTopicPagesContiguous 0 => Subs.php
compactTopicPagesEnable 0 => Display.php 1 => Subs.php
cookieTime 0 => LogInOut.php 1 => ManageServer.php 2 => Profile.php 3 => Register.php 4 => BoardIndex.template.php 5 => Login.template.php
coppaAge 0 => Register.php 1 => Register.template.php
coppaFax 0 => Register.php 1 => Register.template.php
coppaPhone 0 => Register.php 1 => Register.template.php
coppaPost 0 => ManageRegistration.php 1 => Register.php
coppaType 0 => Register.php 1 => Register.template.php
copy_settings 0 => Admin.php
copyright_key 0 => Admin.php 1 => Subs.php
countChildPosts 0 => BoardIndex.php 1 => MessageIndex.php
custom_avatar_dir 0 => ManageAttachments.php 1 => Profile.php 2 => Subs-Graphics.php 3 => Subs-Package.php
custom_avatar_enabled 0 => ManageAttachments.php 1 => Profile.php 2 => Subs-Graphics.php
custom_avatar_url 0 => Load.php 1 => Profile.php 2 => Subs.php
databaseSession_enable 0 => Load.php
databaseSession_lifetime 0 => Load.php
databaseSession_loose 0 => Load.php
defaultMaxMembers 0 => Groups.php 1 => Load.php 2 => ManageMembers.php 3 => Memberlist.php 4 => Who.php
defaultMaxMessages 0 => Display.php 1 => Load.php 2 => ManageAttachments.php 3 => ManageBans.php 4 => ManageErrors.php 5 => MessageIndex.php 6 => ModerationCenter.php 7 => PersonalMessage.php 8 => Profile.php 9 => Recent.php 10 => SplitTopics.php 11 => index.php
defaultMaxTopics 0 => Load.php 1 => MessageIndex.php 2 => Recent.php 3 => SplitTopics.php 4 => index.php
default_personal_text 0 => Subs-Members.php
default_timezone 0 => Load.php 1 => install.php
deleted 0 => Boardnation.php
disableCheckUA 0 => Load.php 1 => Security.php
disableEntityCheck 0 => Load.php
disableHashTime 0 => Subs.php
disableHostnameLookup 0 => ManageBans.php 1 => Profile.php 2 => Security.php 3 => ManageBans.template.php
disableQueryCheck 0 => Database.php 1 => Subs-Db-mysql.php 2 => Subs-Db-postgresql.php 3 => install.php
disableRegisterCheck 0 => Subs-Members.php
disableTemplateEval 0 => Load.php
disable_log_report 0 => SendTopic.php
disable_smf_js 0 => Admin.template.php 1 => ManageSmileys.template.php 2 => Packages.template.php 3 => Themes.template.php
disable_wysiwyg 0 => Subs-Post.php 1 => Post.template.php 2 => Profile.template.php
disabledBBC 0 => ManagePosts.php 1 => Subs-Post.php 2 => Subs.php
disabled_profile_fields 0 => Display.php 1 => Memberlist.php 2 => ModSettings.php 3 => Profile.php
disallow_sendBody 0 => Post.php 1 => Subs-Post.php 2 => Profile.template.php
displayFields 0 => Display.template.php
edit_disable_time 0 => Display.php 1 => Post.php 2 => Profile.php 3 => Recent.php 4 => RemoveTopic.php
edit_wait_time 0 => Post.php
email 0 => Constants.php 1 => Boardnation.php
enableAllMessages 0 => Display.php 1 => MessageIndex.php 2 => Recent.php
enableBBC 0 => Subs-Post.php 1 => Subs.php
enableCompressedOutput 0 => SSI.php 1 => Admin.php 2 => Display.php 3 => DumpDatabase.php 4 => Load.php 5 => News.php 6 => index.php
enableEmbeddedFlash 0 => Subs.php
enableErrorLogging 0 => Errors.php 1 => changelog.txt
enableParticipation 0 => MessageIndex.php 1 => Recent.php 2 => Search.php 3 => MessageIndex.template.php 4 => Recent.template.php
enablePostHTML 0 => Subs.php
enablePreviousNext 0 => Display.php
enableReportPM 0 => PersonalMessage.php 1 => PersonalMessage.template.php
enableSpellChecking 0 => Display.php 1 => PersonalMessage.php 2 => Post.php 3 => Profile.php 4 => Search.php
enableStickyTopics 0 => Display.php 1 => LockTopic.php 2 => MessageIndex.php 3 => Post.php 4 => Recent.php 5 => Search.php 6 => SplitTopics.php 7 => MessageIndex.template.php 8 => Recent.template.php 9 => Admin.template.php
enableVBStyleLogin 0 => BoardIndex.php 1 => Subs.php
enable_buddylist 0 => Load.php 1 => Profile.php 2 => Subs-Post.php 3 => PersonalMessage.template.php
failed_login_threshold 0 => LogInOut.php
fixLongWords 0 => Subs.php
forum_alias_urls 0 => Load.php 1 => Subs-Auth.php
gadmin 0 => Boardnation.php 1 => Load.php
gadmin_subdomain 0 => Boardnation.php
globalCookies 0 => Load.php 1 => Security.php 2 => Subs-Auth.php
global_character_set 0 => Load.php 1 => ManageMaintenance.php 2 => ScheduledTasks.php 3 => Subs.php
guest_hideContacts 0 => Display.php 1 => Load.php 2 => Memberlist.php 3 => News.php
guest_post_no_email 0 => Post.php 1 => Post.template.php 2 => Wireless.template.php
hitStats 0 => Stats.template.php 1 => Xml.template.php 2 => index.php
host_to_dis 0 => Subs.php
hotTopicPosts 0 => Display.php 1 => MessageIndex.php 2 => Recent.php 3 => Search.php 4 => MessageIndex.template.php 5 => Recent.template.php
hotTopicVeryPosts 0 => Display.php 1 => MessageIndex.php 2 => Recent.php 3 => Search.php 4 => MessageIndex.template.php 5 => Recent.template.php
integrate_activate 0 => ManageMembers.php 1 => Profile.php 2 => Register.php
integrate_buffer 0 => Subs.php
integrate_change_member_data 0 => Subs.php
integrate_delete_member 0 => Subs-Members.php
integrate_egg_nog 0 => ViewQuery.php
integrate_exit 0 => Subs.php
integrate_fix_url 0 => News.php
integrate_login 0 => LogInOut.php
integrate_logout 0 => LogInOut.php
integrate_magic_quotes 0 => QueryString.php
integrate_outgoing_email 0 => Subs-Post.php
integrate_personal_message 0 => Subs-Post.php
integrate_pre_include 0 => Load.php
integrate_pre_load 0 => Load.php
integrate_redirect 0 => Subs.php
integrate_register 0 => Subs-Members.php
integrate_reset_pass 0 => Profile.php 1 => Reminder.php 2 => Subs-Auth.php
integrate_validate_login 0 => LogInOut.php
integrate_verify_password 0 => Profile.php 1 => Security.php
integrate_verify_user 0 => Load.php
integrate_whos_online 0 => Who.php
karmaApplaudLabel 0 => Display.template.php 1 => PersonalMessage.template.php 2 => Profile.template.php
karmaLabel 0 => Display.template.php 1 => PersonalMessage.template.php 2 => Profile.template.php
karmaMinPosts 0 => Karma.php 1 => Load.php
karmaMode 0 => Karma.php 1 => Load.php 2 => News.php 3 => Profile.php 4 => Display.template.php 5 => PersonalMessage.template.php 6 => Profile.template.php
karmaSmiteLabel 0 => Display.template.php 1 => PersonalMessage.template.php 2 => Profile.template.php
karmaTimeRestrictAdmins 0 => Karma.php
karmaWaitTime 0 => Karma.php
knownThemes 0 => Load.php 1 => Packages.php 2 => Profile.php 3 => Themes.php
language 0 => Boardnation.php
lastActive 0 => Subs.php 1 => BoardIndex.template.php
last_mod_report_action 0 => Security.php
latestMember 0 => Boardnation.php 1 => ManageNews.php 2 => Post.php 3 => Profile.php 4 => Subs.php
latestRealName 0 => Boardnation.php 1 => ManageNews.php 2 => Subs.php
load_average 0 => Load.php 1 => ScheduledTasks.php
loadavg_allunread 0 => Recent.php
loadavg_auto_opt 0 => ScheduledTasks.php
loadavg_enable 0 => Load.php
loadavg_forum 0 => Load.php
loadavg_search 0 => PersonalMessage.php 1 => Search.php
loadavg_show_posts 0 => Profile.php
loadavg_unreadreplies 0 => Recent.php
localCookies 0 => Security.php 1 => Subs-Auth.php
mail_from 0 => Subs-Post.php
mail_limit 0 => ScheduledTasks.php 1 => Subs-Post.php
mail_next_send 0 => Load.php 1 => ScheduledTasks.php
mail_no_message_id 0 => Subs-Post.php
mail_quantity 0 => ScheduledTasks.php
mail_queue 0 => ManageNews.php 1 => Post.php 2 => Subs-Post.php
mail_recent 0 => ScheduledTasks.php 1 => Subs-Post.php
mail_strip_carriage 0 => ScheduledTasks.php 1 => Subs-Post.php
mail_type 0 => ScheduledTasks.php 1 => Subs-Post.php
maxMsgID 0 => SSI.php 1 => Display.php 2 => Load.php 3 => ManageMaintenance.php 4 => MessageIndex.php 5 => MoveTopic.php 6 => News.php 7 => Recent.php 8 => RemoveTopic.php 9 => Search.php 10 => SplitTopics.php 11 => Subs-BoardIndex.php 12 => Subs-Boards.php 13 => Subs-Post.php 14 => Subs-Recent.php
max_image_height 0 => Display.php 1 => Subs-Post.php 2 => Subs.php
max_image_width 0 => Display.php 1 => Subs-Post.php 2 => Subs.php
max_messageLength 0 => ManagePosts.php 1 => PersonalMessage.php 2 => Post.php
max_pm_recipients 0 => ModSettings.php 1 => PersonalMessage.php
memberCount 0 => Load.php 1 => changelog.txt
memberlist_cache 0 => Memberlist.php
memberlist_updated 0 => Memberlist.php
messageIconChecks_disable 0 => SSI.php 1 => Display.php 2 => MessageIndex.php 3 => Recent.php 4 => Search.php
messageIcons_enable 0 => ManageSmileys.php 1 => Subs-Editor.php
modlog_enabled 0 => Subs.php
mostDate 0 => Stats.php 1 => BoardIndex.template.php
mostOnline 0 => Stats.php 1 => Subs-MembersOnline.php 2 => BoardIndex.template.php
mostOnlineToday 0 => Subs-MembersOnline.php 1 => BoardIndex.template.php
mostOnlineUpdated 0 => Subs-MembersOnline.php
new_avatar_data 0 => Profile.php 1 => Subs-Graphics.php
news 0 => ManageNews.php 1 => Subs.php
next_task_time 0 => Load.php 1 => ScheduledTasks.php
notify_new_registration 0 => Subs-Post.php 1 => Register.template.php
number_format 0 => Load.php
oldTopicDays 0 => Post.php
onlineEnable 0 => Display.template.php 1 => PersonalMessage.template.php
package_disable_cache 0 => Subs-Package.php
package_make_backups 0 => Packages.php 1 => Subs-Package.php
package_path 0 => Subs-Package.php
package_port 0 => PackageGet.php 1 => Packages.php 2 => Subs-Package.php
package_server 0 => PackageGet.php 1 => Packages.php 2 => Subs-Package.php
package_username 0 => PackageGet.php 1 => Packages.php 2 => Subs-Package.php
password_strength 0 => Subs-Auth.php 1 => Register.template.php 2 => Reminder.template.php 3 => Errors.english.php
permission_enable_deny 0 => Load.php 1 => ManagePermissions.php 2 => Reports.php 3 => ManagePermissions.template.php
permission_enable_postgroups 0 => ManageMembergroups.php 1 => ManageNews.php 2 => ManagePermissions.php 3 => Reports.php 4 => ManageMembergroups.template.php
plan 0 => Boardnation.php
plan_actions 0 => Boardnation.php 1 => index.php
plan_perms 0 => Boardnation.php
pm_posts_per_hour 0 => ModSettings.php 1 => PersonalMessage.php
pm_posts_verification 0 => ModSettings.php 1 => PersonalMessage.php
pm_spam_settings 0 => ModSettings.php 1 => PersonalMessage.php
pollMode 0 => Display.php 1 => MessageIndex.php 2 => Post.php 3 => Recent.php 4 => Search.php 5 => MessageIndex.template.php 6 => Recent.template.php
posts_require_captcha 0 => Post.php
queryless_urls 0 => News.php 1 => QueryString.php 2 => Subs.php
recycle_board 0 => SSI.php 1 => News.php 2 => Profile.php 3 => Recent.php 4 => RemoveTopic.php 5 => Search.php 6 => Stats.php 7 => Subs-BoardIndex.php 8 => Subs-Recent.php 9 => Subs.php 10 => ManageBoards.template.php
recycle_enable 0 => SSI.php 1 => News.php 2 => Profile.php 3 => Recent.php 4 => RemoveTopic.php 5 => Search.php 6 => Stats.php 7 => Subs-BoardIndex.php 8 => Subs-Recent.php 9 => Subs.php 10 => ManageBoards.template.php
registration_fields 0 => ModSettings.php 1 => Register.php
registration_method 0 => ManageMembers.php 1 => Register.php 2 => Subs.php 3 => Register.template.php
removeNestedQuotes 0 => PersonalMessage.php 1 => Post.php
requireAgreement 0 => ManageRegistration.php 1 => Register.php
reserveCase 0 => ManageRegistration.php 1 => Subs-Members.php
reserveName 0 => ManageRegistration.php 1 => Subs-Members.php
reserveNames 0 => ManageRegistration.php 1 => Subs-Members.php
reserveUser 0 => ManageRegistration.php 1 => Subs-Members.php
reserveWord 0 => ManageRegistration.php 1 => Subs-Members.php
search_banned_words 0 => Search.php
search_custom_index_config 0 => ManageSearch.php 1 => RemoveTopic.php 2 => Search.php 3 => Subs-Post.php
search_custom_index_resume 0 => ManageSearch.php
search_force_index 0 => Search.php 1 => ManageSearch.template.php
search_index 0 => ManageSearch.php 1 => Search.php 2 => ManageSearch.template.php
search_match_words 0 => Search.php 1 => ManageSearch.template.php
search_max_cached_results 0 => changelog.txt
search_max_results 0 => Search.php
search_method 0 => Search.php
search_pointer 0 => Search.php
search_results_per_page 0 => PersonalMessage.php 1 => Search.php
search_simple_fulltext 0 => Search.php 1 => Search.template.php
search_stopwords 0 => ManageSearch.php 1 => Search.php 2 => Subs-Post.php
search_weight_age 0 => ManageSearch.template.php
search_weight_first_message 0 => ManageSearch.template.php
search_weight_frequency 0 => ManageSearch.template.php
search_weight_length 0 => ManageSearch.template.php
search_weight_sticky 0 => ManageSearch.template.php
search_weight_subject 0 => ManageSearch.template.php
securityDisable 0 => Security.php
send_welcomeEmail 0 => Register.php 1 => Register.template.php
settings_updated 0 => Load.php 1 => Security.php
show_group_membership 0 => ManageMembergroups.php 1 => Profile.php
showsidebarAdmin 0 => Admin.php 1 => ModerationCenter.php
signature_settings 0 => Display.php 1 => ModSettings.php 2 => PersonalMessage.php 3 => Profile.php
simpleSearch 0 => PersonalMessage.php 1 => Search.php
smfVersion 0 => Database.php 1 => Stats.php 2 => Subs-Db-mysql.php 3 => Subs-Db-postgresql.php 4 => Subs-Db-sqlite.php
smiley_enable 0 => ManageSmileys.php 1 => Subs-Editor.php 2 => Subs-Post.php 3 => Subs.php 4 => ManageSmileys.template.php
smiley_sets_default 0 => Load.php 1 => ManageSmileys.php 2 => ManageSmileys.template.php 3 => Profile.template.php
smiley_sets_enable 0 => Load.php 1 => Profile.php
smiley_sets_known 0 => Load.php 1 => ManageSmileys.php 2 => Themes.php
smiley_sets_names 0 => ManageSmileys.php 1 => Themes.php
smileys_dir 0 => ManageSmileys.php 1 => Subs-Package.php
smileys_url 0 => Load.php 1 => ManageSmileys.php 2 => Subs-Editor.php 3 => Subs-Post.php 4 => Subs.php 5 => Help.template.php 6 => ManageSmileys.template.php 7 => Profile.template.php
smtp_host 0 => ScheduledTasks.php 1 => Subs-Post.php
smtp_password 0 => Subs-Post.php
smtp_port 0 => Subs-Post.php
smtp_username 0 => Subs-Post.php
spamWaitTime 0 => Subs.php
theme_allow 0 => Load.php 1 => Profile.php 2 => Themes.php 3 => Themes.template.php
theme_guests 0 => Load.php 1 => Themes.php 2 => Themes.template.php
timeLoadPageEnable 0 => Subs.php
time_format 0 => Load.php 1 => ManageNews.php 2 => ScheduledTasks.php
time_offset 0 => SSI.php 1 => BoardIndex.php 2 => Profile.php 3 => Subs.php
titlesEnable 0 => Load.php 1 => Profile.php 2 => Profile.template.php
todayMod 0 => Subs.php
topbottomEnable 0 => Display.template.php 1 => MessageIndex.template.php
topicSummaryPosts 0 => Post.php
totalMembers 0 => SSI.php 1 => Load.php 2 => Memberlist.php 3 => Stats.php 4 => Subs-Members.php 5 => Subs.php
totalMessages 0 => SSI.php 1 => ManageSearch.php 2 => News.php 3 => Profile.php 4 => Recent.php 5 => Stats.php 6 => Subs.php
totalTopics 0 => SSI.php 1 => Profile.php 2 => Stats.php 3 => Subs.php
trackStats 0 => BoardIndex.php 1 => Subs.php
unapprovedMembers 0 => LogInOut.php 1 => ManageMembers.php 2 => Profile.php 3 => Subs.php
userLanguage 0 => Load.php 1 => ManageMembers.php 2 => PersonalMessage.php 3 => Post.php 4 => Profile.php 5 => Register.php 6 => SendTopic.php 7 => Subs-Post.php 8 => Profile.template.php
user_limit 0 => ModSettings.php 1 => Profile.php
visual_verification_type 0 => ManageRegistration.php 1 => Register.php 2 => Subs-Graphics.php 3 => Register.template.php
warn_enabled 0 => ModerationCenter.php
warning_enable 0 => ModSettings.php 1 => Profile.php
warning_moderate 0 => Profile.php 1 => Security.php 2 => Profile.template.php
warning_mute 0 => Profile.php 1 => Security.php 2 => Profile.template.php
warning_settings 0 => ModSettings.php 1 => ModerationCenter.php 2 => Profile.php
warning_watch 0 => ModSettings.php 1 => ModerationCenter.php 2 => Profile.php 3 => Profile.template.php
who_enabled 0 => BoardIndex.php 1 => Profile.php 2 => Subs.php 3 => Who.php
xmlnews_enable 0 => News.php 1 => index.template.php
xmlnews_maxlen 0 => News.php