We use Empirix. While it's good for doing rote "click here, then here, look for this string" types of testing, it's completely GUI-based and unscriptable from the command line. We have to run it manually as opposed to making it part of our build. In its favor it's better at testing Javascript and the like because it runs its own copy of IE. Windows only, natch.

We also use Grinder, an open-source tool for load testing (although it can be used for unit testing too). It's Java and daemon-based with an optional GUI, and very flexible.