If you ever wondered how some of the standard .NET classes do the voodoo that they do, now you can find out.  Check out Reflector for .NET.  From the site:

“Reflector is a class browser, decompiler and XML documentation browser for .NET components (assemblies). It features assembly and namespace views, type and member search, reference search, IL disassembler, C# decompiler, VB decompiler, C# XML documentation viewer, MSDN help viewer, dependency trees, supertype/subtype hierarchies and resource viewers. Function prototypes are displayed in C# and VB syntax.”