As Firefox 3 gets ramped up, there are nearly 3000 add-ons that need to get updated to some degree. Write tools (web or XULRunner) to look in add-ons and find things that developers will need to update. You'll want to work with the Mozilla documentation and evangelism teams to figure out what you're looking for and what to recommend to users.
Resources: mfinkle
== Make FUEL work with Firefox 2 ==
Mozilla's [http://wiki.mozilla.org/FUEL FUEL] (Firefox User Extension Library) is a JavaScript Library designed to help developers build extensions using terminology and interfaces that are more familiar to them. Currently it works with Firefox 3, but it would be helpful to have it work with Firefox 2 as well. Work toward having the existing [http://mxr.mozilla.org/seamonkey/find?string=fuel%2Ftest%2Fbrowser_ FUEL Tests] pass for Firefox 2.
Resources: mfinkle