As we all know Firefox is a fastest growing popular web browser.There are lots of free download able extensions, add-ons, themes available on the internet for firefox.I am listing top 10 firefox themes of Dec 2009 depends on there popularity of weekly downloads.
Customize look and feel of your browser with the following themes.So use this themes and try with your browser to make your web experience more better.
1.NASA Night Launch

Dark theme for Firefox. Inspired by the night launch of STS-116.It’s a dark theme so this one is mostly for people running dark desktops. I’m really interested in getting feedback from some of these people about how the contrast/levels work for them.
2.ACE Safari Foxdie (Blue)

All-in-one Mac style theme! see the full pack here
3.Noia 2.0 (eXtreme)

This is a fully skinned version. This theme is based on the Noia 2.0 icon set by Carlitus.To use the Noia theme option. First, you need to enable the Noia theme option. Then access the Noia theme option menu.To enable Type “about:config” in the address bar then set “signed.applets.codebase_principal_support” to “true”
4.myFireFox

Myfirefox is the theme of the most perfectly simulating Internet Explorer 8 by far.It can work perfectly in Windows 7 .
5.Vista-aero
The most IE8-like theme with Vista Aero style! We can disable color tab of Vista-aero By click option at the end of the tabbar ,disable useColorTab.
6.Silvermel
This theme is a modification from the fantastic theme Charamel.Silvermel is offered as bundle – it installs “Silvermel and Charamel XT” extension to support font uppercase and letter spacing for labels on Firefox’s sidebars, Thunderbird’s folder pane, Thunderbird’s Address Book and Thunderbird’s Account Configuration window. The extension also colorizes the url bar according to security state.The extension only applies if Silvermel is the used theme.
7.Gradient iCool (Blue)
A modern glassy dark theme with unique animated interface. A perfect mixture of black and blue for your ultimate Firefox browser.
8.RedShift
The next generation Firefox theme is here.RedShift V3 pushes Firefox to it’s limits. Fully skinned and fully functional, RedShift V3 gives you the aesthetic pleasure you want with an advanced program.
9.Black Steel
A dark sleek theme for the firefox browser.
10.Chromifox Extreme
A coat of Chrome for Firefox. Chromifox is a bright and soft blue theme for Firefox on Windows, Linux, and Mac OS X, inspired by the appearance of the
Google Chrome browser and its open-source roots, Chromium.
Recommended Firefox theme from Tech Bucket specially for Xmas :
Tinseltown

Tinseltown is a Christmas theme with holiday imagery including Christmas lights, snow, reindeer, presents and more. This theme is made even better with great Christmas icons from Watiworks and a semi-transparent URL bar. Get in the holiday spirit!
Which one did you like the most? Let us know from your feedback.
Great list,
Im currently using the black steel theme but im always changing.It’s a bit late for the christms thenes but i will try some of the others,
Pau;.