.Net reflector is a really good tool. You can see the content of any assembly very easily. But it’s not really easy to see the full content of a class, or a library with it.
The File Disassembler add-in is a totally crazy stuff. You can take any assembly and totally disassemble it. It even creates the .csproj so that you just have to open the project in Visual Studio. But don’t get too excited if the code is obfuscated you will get some “empty” methods with just this comment :
// This item is obfuscated and can not be translated.
By the way. As you can see from the .net reflector video, you can register in the context menu for any DLL and EXE assembly by executing it with the /register parameter.