generates encoded signatures to add to update.rdf and install.rdf in secure firefox 3 toolbars

Mozilla's main page for this sort of thing

mozilla's how-to documentation for mccoy

Mozilla is currently testing out something called "Weave," a tool that would allow you to synchronize your content on multiple browsers, via a hosting option similar to what Google does.

This goes a step beyond Google, because Mozilla is, of course, a desktop application. So Mozilla Weave would have access to your desktop behavior and the stuff you store on their servers.

mozCC is an extension for Mozilla-based browsers, including Mozilla Firefox, Flock, Mozilla and Netscape, which provides a convenient way to examine Creative Commons licenses embedded in web pages. It’s at least twice as good as View Source.

Drop files into attachment boxes instead of browse for them or type in the filename. Drop multiple files and fill all the entries. In some websites it allows to add new upload files: in Gmail is possible to drop the files directly over the "Attach a file" link.

A Sidebar allows to drop files from a listing