We don't use Google Website Optimizer, which I won't recommend to anyone. We're using a .NET framework that I won't name because we're probably going to transition off of it.

I enjoy Rails a lot more than I enjoy .NET, but give me some credit: looking at new languages doesn't cause my brain to throw a WTFCodeIsCamelCasedException.

By the way, Fog Creek isn't strictly a MS shop. There is a lot of "best tool for the job" going on, including e.g. Python being used as utility glue.