Three20
Three20 iOS Library
The Facebook Open Source Library for iOS originally created by Joe Hewitt.
Three20 Chrome Extension
This very simple extension adds an 'tt' command to the Chrome Omnibox. For example, typing 'tt TTView' will bring up a list of all class names in the Three20 Library API matching 'TTView'—selecting a list item navigates to the relevant Three20 API Reference URL on api.three20.info.