We’ve got a new page on the Mozilla Web Dev blog about getting involved.
On it, you’ll find information about some of our biggest projects, including Addons and Support. There are links to the project pages on the Mozilla Wiki, names of people to contact including IRC handles, and links to the source, tests and bug lists.
This page is a starting point. At the bottom you’ll find a link to a list of (hopefully) all the websites we maintain.