I am sure that you have heard people talk about needing to test your code. Well now you can do that testing in an integrated manner. Visual Studio Team System (VSTS) has unit testing built in. If you have used NUnit you are already 90 % of the way to learning how the testing work in VSTS.
If that wasn't enough, you can create stubs, by just simply right clicking on the appropriate method and you are taken to a Test Explorer which allows you to select the methods for testing. Just in case that wasn't enough, it will create the code so that you just need to customize it.
To find out more: attend a live event : www.msdnevents.com