Design Pattern and User Interface Library from Yahoo!
Everyone have blogged about "Design Pattern Library (Design Pattern Library)":http://developer.yahoo.net/ypatterns/ and "User Interface Library (User Interface Library)":http://developer.yahoo.net/yui/ from "Yahoo! Developer Network (Yahoo! Developer Network)":http://developer.yahoo.net/. Let me do my bit for the archive.
"Download Yahoo! UI Library (Download Yahoo! UI Library)":http://developer.yahoo.net/yui/downloads/yui.zip
The *Yahoo! Design Pattern Library* is an evolving set of sophisticated design guidelines for building web pages and applications. The design patterns do not require the Yahoo! UI Library components, although using the UI Library can help you more easily implement the patterns.
The Yahoo! UI Library downloads contains documentations, source files and examples of the various libraries.
While you are at it, don't forget to read the article, "Graded Browser Support (Graded Browser Support)":http://developer.yahoo.net/yui/articles/gbs/gbs.html By Nate Koechley, Senior Web Developer at Yahoo! Inc.