I've been browsing through the Javascript widget library provided freely by Yahoo!, there are some nice examples here showing off some of the features on offer:

Yahoo! UI Library (YUI)

A few years back this would have been called a DHTML library, but somehow that term has fallen out of fashion despite the underlying technologies being the same, that's the marketing of technology for you ;-)

John Collins

I have been writing about web technology and software development since 2001. I am the developer of the Alpha Framework for PHP, and the Five.Today personal productivity app. I love open source, technology, and economics.