After three weeks of work, the first draft of Extend Firefox is complete and available on this website.
This document explores the process for creating an extension for Firefox 1.5. The topics covered include adding a button to the status bar, adding a menu item, adding a preference pane. The tutorial goes in depth, with copious code samples, how to actually do something with the buttons once they are added. The sample code is all from program called Home Page Scheduler that was developed for this tutorial.
I was a member of the team of Georgia Tech students who developed this document as part of a technical communications class.