I've been told of two addins for this great tool Reflector.
One is the File Disassembler addin, which you can use to generate code, in any language, from any assembly. This maybe useful for translating from one language to another, or to view the code in Visual Studio rather than in Reflector, but the truth is I haven't got the opportunity to need it yet.
The other addin, which I do use a lot, is the Code Metrics Addin. This one computes several code quality metrics of the assembly, such as the number of members of a class, the cyclomatic complexity, or the distance to the main sequence.
Since the link for downloading seems to be broken, I've upload it here.