Kongregate, one of the most famous Flash games portals, now supports Unity games. Unity is a powerful development environment which allows you to create web, mobile, and even console games.
To celebrate the partnership, they launched a game development contest.
The 10 best Unity games published before February 15, 2011 will win cash prizes for a total of $25,000.
I just installed Unity, and I am start playing with it, so expect some quick tutorial soon.
Meanwhile take a look at the official page.