I wrote about and tested www.whirled.com a few weeks back. It is a slick system by which game developers can create single and multiplayer games, and also earn money with them through micro transactions.
They have a new contest that just started and will run for three months, and possibly every three months after. There are 5 prizes in each of the single player and multiplayer categories ranging from $7500 - $1000 for multiplayer games and $2000 - $250 for single player games.
The contest looks like it will be pretty good, and I like what Whirled is doing, but there is one small catch:
Much like the Mochi ad system games and contests, you grant them a non-exclusive license to use or not use your game when you submit it to the contest. The license includes giving them the right to create derivative works from your game (much like the Mochi License). I have never heard of Mochi doing such a thing, but it is their right. By submitting your game to the Whirled contest you very well could win some good money and make even more with micro transactions, but you run a slight risk of your content being used in a way that you don't approve of. It is probably worth the trouble if you have a game that is good enough to with the $7500, but still it could be a slight concern.
Many sites and contests have this provision, so it might not be much of a concern to those who enter contests all of the time. The potential rewards look very good, but just make sure you read the fine print when you submit because your game might already be licensed out or sponsored in a way that prevents you from using it in this contest.