(From the NY Times -- sorry if this has already been posted somewhere that I didn't notice. Can't vouch for any of this info from personal experience, but glad to see the Car-Free concept getting some attention as a legitimate topic in the mainstream media...)
Los Angeles on $100 a Day
The Frugal Traveler discovers the first rule of saving in the city of highways: rent a bike.
Slide Show: Los Angeles On Two Wheels