Check out this interesting blog from TIME.com's "It's Your Money":

"Adam Greenfield, a 29-year-old filmmaker born in England and now residing in San Francisco, decided that for an entire year, he would not get into any sort of automobile. No SUVs, taxis, or motorcycles. Not even a ride in a hybrid or electric car. His bicycle took him nearly everywhere he needed to go.

What was the point? For one thing, to prove that he could do it—and that others might be able to follow his lead, in ways big and small. . . . "