We just recently created a project on CodePlex that is an Open Source Debugger Extension project called ODbgExt. This is an extension is going to be created by the community. So everyone will have a say in what happens with it. The NTDebugging blog has more information on this but I wanted to copy the goals of the extension.
As you can see, these are some great ideas and an extension that has these abilities would be a very valuable tool to have. Please go check out the project and get involved.