As you probably know, we don't ship a code coverage tool with Visual Studio .NET. However, it is handy to be able to report which IL instructions have been executed and how much time was spent executing them. With large codebases, it's often difficult to ensure that all possible paths have been tested, and a tool like this is invaluable. Stuart Richardson, from our UK Solutions Development Centre, has created a free coverage tool called CoverageEye.NET that can be downloaded from GotDotNet. It operates at the IL level, so it works for all .NET languages. Check it out.