The "Next Generation Design Competition" for 2010 is accepting entries until January 29, 2010. Here's the website.
Entrants are urged to "provide one small (but brilliant and elegant) fix—leading to an incremental (or dramatic) change in sustainability. Your fix needn’t have anything to do with “environmentalist engineering” to make a difference. Concentrate on what you know best, are aching to improve in a way that deploys your training and imagination."
The 2008 winner was a Las Vegas native with a great water purification idea. He designed a special tarpaulin using passive solar heat and ultraviolet radiation to disinfect the water (a World Health Organization–approved purification method that takes only five hours).
Sponsor of the contest is metropolismag.com, an online design site. The prize is $10,000 and is open to young designers and architects and students.