Like the default Firefox theme, but find it to be a little too colorful for its own good? Then you might want to check out the Firefox theme – MonoChrome. It brings Firefox back to basics with everything turned black and white and grey all over.
Looking for a darker Firefox theme, that has some aspects of the new Firefox 4.0 look built inside? If so, check out NightShade. This slick dark theme is almost a perfect representation of how a great dark theme should look.