r1k /// hmm, I didn't know about it and thanks!

Agree with r1k. A little bit of more contrast will look fine.

And pls, use transparency and try cutting the unused canvas in the top, bottom, left and right.

looks nice, but I think you could go with a little more contrast.  Heres a quick adjustment done in photoshop (may be a little more saturated than what you want) :

imageshack.us/a/img835/3183/blueboxedit.png

you may need to make the background transparent to get it accepted.

I like the concept and the colors. But some strokes looks mmm, not very good. Try using some aliasing in the border lines.

This thing just begs to be animated!