I think I can say that I know most of the relevant development tools related with the .NET world, so it's obviously not every day that I stumble upon a new tool worth of notice. But today (or rather tonight) was one of those days (or nights). Even more relevant is the fact that this one is free (at least for know, while its considered a beta version).
I'm talking about NCrunch (http://www.ncrunch.net/). It's a tool targeted for developers using Visual Studio and doing TDD. It aims to decrease the amount of time we loose compiling and runing our unit tests, by not requiring us to do it at all! That is, it compiles and runs our tests in background automatically. Even before we save the file with the unit tests source code!
I'm not going to write a full review, but I dare you to use a handful of minutes looking at the video presented in the NCrunch homepage to see the awesome features available.
Happy coding and testing!