• Car-sharing

There's a growing movement to reduce driving by sharing cars. This can be as informal as sharing vehicles among housemates, friends, and neighbors, or formal through programs such as Flexcar or Zipcar.

Car-sharing has real environmental benefits. People tend to drive less, plan trips more efficiently, and share trips. Also, a lot of the environmental impact of a car is in its manufacture, so owning fewer cars means less pollution. 

Here's a great article about car-sharing by Alan Durning of Sightline. Here's an example of Seattle City government encouraging car-sharing.