Now that the InfoPath team has release the new SDK, I am inspired to do something new. I love the fact that we have XmlComments in C# and that it has the support including comments from external files. This makes it easier to separate the comments so that the doc people can work on them without affecting your code.  The problems right now are:
1. There is no way for a dev to put in the comments and then externalize them (rip them out and put into a file with the correct tags)
2. There is no editor for the comments

My idea is to solve both these problems with InfoPath as an editor, and an extension to VS for the ripping. If anyone has any ideas or knows of existing projects out there that can help, I would love to hear from you. I plan to start working on this over the next month and then post something to GotDotNet.