One thing I really love about TextMate is how extendible/customizable it’s themes are. I’m a visual coder and having a theme that I can customize to my coding style really speeds up development for me.
The Macromates website has a pretty extensive theme gallery with downloads of dozens of themes but other than that, there isn’t much else out there in terms of “repositories” for themes.
Today a new site dedicated specifically to TextMate themes launched, called TM Themes.
Right now the collection is quite slim but once that is expanded it should be much easier to find themes you like. There’s a rating and comment feature built in also to help you narrow down the good from the bad.
Be sure to check out the site and upload any custom themes you’ve created!