Another plugin for VisualStudio which has been around for a while, helps you write code documentation for your c# classes. This is the summary from Roland Weigelt's blog about his tool:
GhostDoc is a free add-in for Visual Studio that automatically generates XML documentation comments for C#. Either by using existing documentation inherited from base classes or implemented interfaces, or by deducing comments from name and type of e.g. methods, properties or parameters.
Just right click the code and select "Document This" from the popup menu:
Cross-posted from my blog at http://weblogs.asp.net/jdanforth