Moodlebites is online training for Moodlers (administrators, teachers, theme designers, etc.) developed and managed by HRDNZ. On their Youtube channel they have loads of great videos pulled right from the courses that are a great source of information for theme designing, Moodle course creation, administrating a Moodle site and more.
Check out the complete collection of videos here: http://www.youtube.com/user/hrdnzmoodlepartner
This was one of the videos that first caught my eye: A simple and effective way to use a browser extension to help find and change colors on your theme. Very cool stuff.
Direct video link: http://www.youtube.com/watch?v=gQrBMU-xIyk