Currently being updated for Moodle 2.5 through Moodle 3.0. Check back soon! :)
Moodlebook is a three-column that emulates the look and feel of Facebook.
It is based on the Decaf fluid-width theme for Moodle that was created by Lei Zhang. It improves usability by shifting setting blocks to top of the page, so called "Moodle awesome bar".
For developers, It transfers the performance info into a colorful floated bar at bottom of the page, which brings the performance awareness as well as improves usability.