Easy to use namespace-detection templates:

• {{main other}} – For article templates.
• {{talk other}} – For talk page templates.
• {{user other}} – For user page templates.
• {{wikipedia other}} – For detecting "Wikipedia:" pages.
• {{file other}} – For file (image) templates.
• {{template other}} – For detecting template pages.
• {{help other}} – For help page templates.
• {{category other}} – For category templates.
• {{portal other}} – For portal templates.
• {{book other}} – For detecting book pages.

More complex namespace-detection templates:

• {{namespace detect}} – The very versatile one.
• {{namespace detect showall}} – The extremely versatile one, has input reuse.
• {{talkspace detect}} - For detecting talk pages on various namespaces.
• {{main talk other}} – Separates some namespaces.

Pagename-handling and detection templates:

• {{pgn}} – Can take apart and put together pagenames in several ways.
• {{basepage subpage}} – For detecting if on a basepage, subpage or subsubpage.
• {{if pagename}} – For pattern matching on the pagename.
• {{if pagename multi}} – For pattern matching on the pagename, has input reuse.
• {{IP-user other}} – For detecting IP-user pages.

Technical stuff:

• Wikipedia:Namespace – Lists all the namespaces.
• mw:Help:Magic words – About {{NAMESPACE}} etc.
• mw:Help:Extension:ParserFunctions – About {{#ifeq:|||}} etc.

Template documentation