Every year the car sharing company Zipcar offers a challenge to a group of participants: put your car keys under your mattress for a month and get around soley by your feet, bike or public transit.

2010 participants reduced their driving by 67% and 69% considered going carless.

Participants are given a wealth of resources - including a free Zipcar membership and free driving credit - to help make temporary transition to carlessness. Throw your hat into the ring at Zipcar's Low-Car Diet web site.