I already use Firefox for long time with a default theme, never change it. Search for an alternative resources for Firefox theme only will show only a few selected source - yes you will find it, but with limited theme. From the search that I made, I found some of the best source where you can download a tons of Firefox theme. Maybe a less known source to some of the Firefox users (excluding Mozilla’s site ).

Firefox Themes at Learn Firefox - Run by the CyberNet News crew it is one of the few unique resources out there. Browse by screenshot alphabetical order and find your favorite theme.

Customize.org - Firefox Themes - More Firefox theme you can find here with a help tutorials. Customize.org has a nice navigational system with some good theme in a one place.

DeviantArt’s Firefox Themes - There are tons of themes on DeviantArt, some of them I never seen before. Browse through thumbnail by thumbnail.

via Firefox Fact

Drop by a comments if you had other place to download Firefox theme. Maybe you can share with other.