VSBlogger
At TechEd 2004 I demoed a RSS Reader Add-in for Visual Studio. I finally packaged up the sources and made them available on GotDotNet under the name VSBlogger. It is not as full-featured as some of the other blog readers out there, but the source is available for you to play with and add any new features that you may like.
[Edit: 6/14, 3:57PM] Here is a direct link to the workspace: https://workspaces.gotdotnet.com/vsblogger