Besides pointing you to useful websites and showing you useful productivity tips I will also showcase some of the best tools out there. This is the first of a number of posts which focuses on developer tools.
Lutz Roeder’s .NET Reflector enables you to browse and search through the class hierarchies of .NET assemblies even if you don’t have the code for them.
The README describes the application as follows:
Reflector is a class browser for .NET components. It allows browsing and searching the meta data, IL instructions, resources and XML documentation stored in a .NET assembly.
The .NET Reflector is in my opinion one of the most useful tools for serious .NET developers. It simply allows you to see what happens behind the cover of the .NET framework.