How about making a contest, where you get a small thumbnail image (16*16) and you have to paint it larger (400*400).
It has to be unclear what the original image is, so that you can get easily interesting ideas.

I would really love to see something like this actually happen.
What do you think?

EDIT: hmm no idea why DBA deleted her post :( ... I was just going to reply. Well nevermind.