AppKiDo - sweet

If you're a Cocoa developer then you might want to check out Andy Lee's AppKiDo, a:

free reference tool for Cocoa Objective-C programmers. The goal of AppKiDo is to help you find what you want in the Cocoa documentation. It does this by parsing the header files and the HTML doc files that were installed with your Developer Tools, and presenting the results in a form that is easy to navigate.

As a neophyte Cocoa developer I'm loving this thing (but it would be great if it was able to support other frameworks, like the AddressBook). And, as noted in the comments to this post, it also supports lesser-used frameworks, like AddressBook. Sweet.