Rainbow colors are fine and should be incorporated in a new clean logo (I'll try working on that in Adobe Illustrator).

I believe that we should work on clean, accessible design in parallel with the actual coding process. I could work on several different CSS files and then we could decide, using Canonizer which one is the best. I propose using simple color scheme (three to four colors). I have a few thoughts on navigation and other user interface improvements also (graphic tree view for topics, etc.).