I’ve been having fun working w/ (among others), the ExtJS library (ext.js.com).  In fact, I’m a paid customer, meaning I get access to the SVN tree, which can come in handy. However, the SVN tree doesn’t include the packaged files needed for easy use, as those are currently built as part of the release process by the Ext JS team through a baroque process involving a Windows-only program.  While there are plans to provide tools to customers to make custom builds available on demand, that’s not there yet.  To make my own life easier in the interim, I wrote a script that I run from the root of the svn tree and creates the packaged files.  If you want to work off of the head, it’s handy.