I love playing with TextMate themes. I tend to get bored easily, and besides a proclivity for dark backgrounds that impair readability, I'm always up for variety. That's why I'm pleased to see TM Themes, developed by Garrett Bjerkhoel, hit the TextMate theme scene. The site is starting out with a small collection of themes, but features a simple interface with rollover and full previews, a rating system, comment option and theme uploader. Hopefully it will become a good source for coders to find means of expressing their individual creativity, a trait which many don't realize is innate to the coding species.
The TextMate wiki offers a large collection of user-contributed themes, and there are other collections as well. For the most part, though, the themes are found individually across the web. It's fun to see collections coming together and TextMate fans providing services like this for other users.