I'm using Infinitest for continuous testing when I do java development and i really miss the instant feedback when I develop in .nET
How do I do continuous testing in C# & .NET?
EDIT: I'm not looking for continuous integration, like CruiseControl, TeamCity etc. It's an instant feedback tool that works with your IDE that I'm looking for
If you're using Visual Studio 2008 or 2010, you should take a look at the extension Continuous Testing for Visual Studio.
Note that it does not run the tests when you save, but rather on each build.