http://www.foxmarks.com/
Synchronise your Firefox bookmarks between multiple browsers and online.
http://www.jaduncan.com/2009/02/gears-on-64-bit-gnulinux.html
Builds of Google Gears for 64-bit firefox.
https://jetpack.mozillalabs.com/
Jetpack is a simple language to write almost on-the-fly Firefox plugins. Pretty amazing technology, looks like css / jquery with some custom methods. Beautiful. Hat tip sfllaw.
