Greets!
This is Bart from
OpenGameArt.org. I've run a couple of pixel art contests in the past, and had limited interest because the prize money we're able to offer (generally a total of $150 or less) is understandably not particularly tempting considering the time investment required. Also, there's little motivation to create a small, quick submission due to the fact that you're likely going up against other people who have put a large amount of effort into their work.
Anyway, barring a massive increase in site donations, our budget is what it is, and there's not much getting around it. On the other hand, I thought maybe I could limit the amount of time spent on contest submissions by planning a contest time in advance (perhaps with some general description of what the contest will be about), but then only announcing the actual subject of the contest one hour before the entries are due, thus limiting everyone to a single hour of work. The usual OGA contest rules would apply -- you would retain ownership of your art, but in order to enter it, you would have to agree to release it under a Free license.
So my question is this: If we were to post such a contest, would be people be interested in participating? Please let me know, and if you have other ideas, I'm all ears.

Thanks!
Bart
http://opengameart.org