I've just released a theme called Supr Preppy. It features a dark background with rainbow colored content sections.
This theme was tested on version 1.5.x - 2.5.x of WordPress. It sports all the nifty new features such as widgets, tags, and avatars. Of course, you must be using one of the newer versions of WP to take advantage of them.
Theme cost: $0
Theme license: CC Attribution
Sponsored links: No
You're welcome to have a look at the theme, download and play with it and let me know what you think. Also, I'd like to use this as the official support thread; I'll be subscribing to any replies via RSS.