Winter Holiday Christmas Boom! (for Firefox 3.5)
Not only does this theme enhance your browsing experience by changing the colors and icons of Firefox, it even includes links to great sites and a Christmas-themed videos in the sidebar. All we need now is a large group of people singing Jingle Bellsto set the mood perfectly right!
Xmas (Light) (for Firefox 2.0)
Yes, this is for Firefox 2.0. Yes it looks dated. However that should not stop any self-respecting 2.0 user from using this. This is one of the better Christmas themes for Firefox 2.0!