NDepend offers a wide range of features to let the user analyze a code base.
It is often described as a Swiss Army Knife for .NET developers.
Support for Code Query over LINQ (CQLinq) to easily write custom rules and query code. Test your code in the way it needs to be tested.
NDepend is a full test coverage tool for seasoned developers, managers, and architects that helps ensure the stability, reliability, and cleanliness of code.
Includes full Visual Studio integration.