Miguel Saldana

The winner of this year's second Greener Gadgets Design Competition was the tweet-a-watt, a device that tells your Twitter account how much electricity an appliance is using. But the entry that stole our hearts was the Fastronaut, a boldly colored space-hero toy that is "powered by play." Attach it to your bike and watch as the energy created by pedaling sets its lights flashing and sounds blaring. A patent is pending. So get the kids -- let's play!