Krzysztof Cwalina and the gang have been working on a tool to make it easier for Framework designers to design, review and maintain highly usable APIs... You have to check out Framework Design Studio.
Currently the tool is focused on:
- Listing APIs exposed from a managed code assembly
- Comparing APIs in two versions of an assembly
- Reviewing APIs, commenting on API design, and filing review bugs to a defect database (through a configurable plug-in)
- Exporting API review comments to a Microsoft Word document