Are you constantly hunting the WordPress Codex for functions and template tags? I know I spend a lot of time doing this whenever I am working on a new plugin. Andy Stratton too did the same until he created WPLookup.
WPLookup will take your query and take you to the corresponding WordPress Codex documentation in the function reference and template tags reference. If your search terms are not found, it will send you directly to a documentation search for your terms.
The site is very much in the nascent stages. And, I’m sure there is a lot more that can be added.
One suggestion could be that instead of sending the user directly to WordPress Codex, WPLookup can generate a search results page with a link to the codex article as well a link to the function declaration in the WordPress code using PHPXref.
The search results page can contain other related tags and links to their specific pages as well.
Any other features you would like to see added?