I promised an article in .NET Developer's Journal's June issue a while back. I just received word that the article has made it online for your reading enjoyment: http://dotnet.sys-con.com/read/105646.htm.
Have you ever thought of a killer feature you would love to see in Visual Studio? Maybe you want to add support for a new programming language, or you have an idea for a new GUI designer tool. You can add support for virtually anything to Visual Studio through the SDK.