Bromine is an open source QA tool that uses selenium RC as its testing engine.
It provides project management, OS/browser specification, test-case creation as well as user management.
Check out our screencasts
New release 1/20/2011 - Intuitive and simple web server (or localhost) based bug tracking & reporting system. Uses PHPs built-in SQLite3, no MySql required. Supports any OS with browser.