I just found this framework last Friday and really wanted to pass it along to anyone else using ASP.NET. I have been using NUnit for a while now and really do love the fact of being able to write test and know before pushing out a dll that I haven't broken anything during my latest addition, but with ASP.NET there hasn't been (at least as far as I've seen) a way to test the user interface and logic flow until recently. The ASP.NET team wrote a tool (http://www.codeplex.com/aspnet) for them at some point and a couple months ago they posted it for us to use.
I've only been using this framework for a couple days now but I can not say enough good things about it. With very little work I've been able to write test cases for every login scenario I have to support, to include successful logins, missing user names/passwords, prompting user to contact tech support etc. This framework allows you to navigates to pages, wait for the post-back, capture elements on the page look at the values/properties of controls everything you need to test flow through a application.
Starting this week I will begin showing code that I have come up with to test my own web site to demonstrate this framework, so check back.