With gas prices at a record high and public transit a cost-effective and greener option, now's a good a time to ditch your car. Zipcar is trying to ease the transition with the "Low-Car Diet." Beginning 21 July 2008, they're challenging North Americans to go car-free for a full 30 days. They will replace participants' car keys with a complimentary transit pass, a free one-year Zipcar membership, drive time credit and a number of other perks from local partners. In the New York City area, Zoo York will aid the car-less participants by donating skateboards (pictured).