A TextMate (and Sublime Text) theme HEAVILY based on Monokai by Wimer Hazenberg.
Monokai Dark is a quickly tweaked version of Monokai, changed to a darker background (#141414 to be specific) with a few color changes and tweaks for CSS.
Note: this theme was only tested in Sublime Text. It should be fully compatible with TextMate, but if you come across any errors, please report them and I'll do my best to fix them.