Ruby and Watir
From Scott Hanselman:
The back story is this. I've been trying to find the Holy Grail, or even the 40% Grail of Automated Web UI Testing for at least the last 5 years. We use NUnit for everything, so it'd be cool if whatever we chose could fail NUnit tests.
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And the one I'm currently enamored with is Watir
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Watir is an open source functional testing library for automated tests to be developed and run against a web browser. Cool?
He goes on to show how easy (and intuitive) it is to run unit tests using this tool which automates IE. If you're doing unit testing and developing for the web give his post a read, it is worth it.
Hmm... looks like I might need to look into learning Ruby.