Walnut2, based on icons from art.gnome.org. Includes support for help, inspector, downloadstatusbar, downloadmgr, calendar, quicknote, offline, toolbarext. and many other extensions. Install "About Home Themer" to also theme the about:home page.
Experience all the benefits of Firefox 4 (or later) with the colorful toolbar goodness of Firefox 3! This is one of the best themes, and it does not deserve to die. original theme and idea by: Jeremy Morton. Now with Australis support!