Recently I’ve been analyzing the GUI test automation tools and two of those tools stand out very well.
http://seleniumhq.org/ (Thanks Jalal)
We are currently evaluating those tools and soon I hope we will hook them up to TFS Team Builds for better build results.
So far http://watir.com/ seems to be the champion on simplicity of the implementation and coverage among browsers.
I think soon those tools will shake up the global market in QA Automation testing.
Also it worth to check the OpenQA site for other variaties. http://openqa.org/