CDS showed me a cool new tool today called Rhino Mocks. I have never used mocks before so was impressed nonetheless. Its helping make unit test actual unit test and not block of code that hit DB's or file systems or this, that and the next thing (check out Micheal Feathers post re unit test rules here).
One of the coolest thing is it is written by an up and coming software geek who is only 24 and has a healthy list of accomplishments already. Check out the work of Oren Eini (AKA Ayende Rahien) here