Ui

http://code.google.com/p/aost/ UI-module bases framework for auto-testing web applications, uses Selenium to interface with web sites (written in n Java, Groovy, JQuery, JavaScript), test can be written in Java, Groovy or special Tellurium DSL. )

http://lab.simurai.com/css/umbrui/ cool CCS3 demo (currently works only on webkit-based browsers, i.e. Chrome and Safari)

http://daringfireball.net/2004/04/spray_on_usability good essay about software usability in regards to open source software. Much of what he says is true.