JetBrains makes some great products.  One of those great products is ReShareper.  Resharper is the most intelligent add-in to Visual Studio, ever! With its unrivalled code analysis, superior unit testing solution, and much, much more — ReSharper 4.0 is sure to greatly increase the productivity of any .NET developer.  Another great product is DotTrace. JetBrains dotTrace is the complete profiling solution for .NET. It profiles:

• the performance of .NET Framework 1.1, 2.0 and 3.x applications
• the memory usage of .NET Framework 2.0 and 3.x applications
• ASP.NET applications running on Internet Information Server & ASP.NET Development Server
• Windows services

Check out their software here: http://www.jetbrains.com/products.html