If you don't use ReSharper you're developing with only one arm. If you know about it but don't know if it's worth learning then have a look at 31 Days of ReSharper.

Even better, if watch it being used in anger and download the (33Mb) video of Ayende Rahien demoing Rhino Mocks in a TDD scenario. He uses ReSharper to knock out the code and it’s very cool to see just how quick someone can punch out code if they know how to use their tools properly. (the coding starts after about the 11-12 minute mark). Enjoy.