I recently found out from a friend about MS Research’s Pex. There is some pretty cool stuff you can do with Pex, and the addition of Moles looks like it could be a pretty awesome testing suite. I have only scratched the surface of these tools.
Another cool new toy is NuGet. NuGet offers Gems-like package management for .Net. Cooler still is it is integrated into Visual Studio. You get a Powershell experience within VS to manage your packages. There is a brief intro video from Phil Haack, but I preferred David Ebbo’s extended tutorial.