When working with native code and when working with crash dumps, the Debugging Tools for Windows are an incredibly useful asset.
One of the rarely-used but incredibly-useful capabilities is the support for extensions. There are all sorts of things you can do with these extensions - you have an enormous amount of power. Writing these however is a bit of a black art, and there have been relatively few resources on how to do this.
On MSDN Magazine, however, you can find a short tutorial that walks you through creating a debugging extension, with very detailed and clear explanations along the way. Definitely worth checking out.