I’ve found two themes for firefox and thunderbird that I’m so pleased with them I have to promote them a bit :-). They are Charamel and Silvermel created by Kurt Freudenthal. I discovered them thanks to Chewie. So, what I like about them is: Works with newer versions of Mozilla firefox and thunderbird (Including version 3 beta 4) It’s got really nice colours and a nice layout. It works fine under linux and Mac OS X.