Biking from here to REI (7.6 miles each way) would save about 12 pounds of CO2 emissions. (I do wonder as the emissions data is worse for post 1997 cars, is that just the result of the horrid performance of the american auto industry with respect to emissions controls?)
Also center for a new american dream's turn the tide program is trying to negotiate for a mileage based insurance.
One of the bigger problems with trying to create alternatives to driving is that the automobile has a huge fixed cost, and relatively small variable cost. Once you have a car each additional mile is relatively cheap, as a result there is little incentive to do drive less. However if more of the cost were variable, it could become cost effective to try alternatives.
As an extra idea, I wonder if it'd be a good idea to raise taxes on oil to pay for the Iraq occupation (or other military adventures designed to secure an oil supply) instead of diffusing that cost to the entire society.