It was pretty nice to be able to use Venkman to debug some of the extension wizard code.
Paul Medlock has been sending in some patches too. He sent in a XUL formatter to keep the source code pretty in the editor. He also sent in some intellisense-like features for XUL. We are running into some of the limitations of the Mozilla editor in the process.
Contributing to XUL Explorer just got easier. A bugzilla component for XUL Explorer was added recently. You can now use bugzilla to file bugs or submit patches. Here are some useful links for contributing:
Feedback, bugs and patches welcome.