GAT (the Guidance Automation Toolkit) is an interesting package that allows you to easily create VS extensions, wizards, template engines and similar things, without going through all the hassle that the Visual Studio SDK (used to be VSIP) still involves. The new Dec 2005 CTP runs on VS 2005 RTM, which makes the whole thing much more useful. They have also updated the templating engine, so it's now the same as in the current DSL tools CTP.