XML documentation helper tool
Travis Illig has a great Visual Studio add-in that allows you to see a preview of your XML document comments in real-time, as you edit the comments.
CR_Documentor offers the ability to choose the level of tags you want to be "compatible" with, the manner in which "unrecognized" tags are handled, and other formatting options. It also offers context-menu support to aid in working with XML documentation comments, including inserting templates, embedding selections in templates, toggling outlining on XML doc comments, and toggling visibility of the CR_Documentor window.
CR_Documentor is based on the code of the original Documentor from Lutz Roeder (of .NET Reflector's fame).
It's good to see that Documentor did not disappear completely and comes back nicely improved!
PS: Reflector has been updated with support for web proxies, string search, Google and MSDN search, font customization, print preview, and generics fixes. A great release!