Maybe biking is a great idea.

The most efficient car is the one that you don't have and the second most efficient car is the one not in use. For me its the latter as I caved in and bought a car a few months back. But I still bike because it is sustainable. You can protest oil pipelines and offshore drilling with actions that speak louder than words. Even if you don't agree with man made climate change, we can all agree on the other evils associated with drilling and burning oil. From deforestation, to oil spills, wars, acid rain, smog, etc.

And for the I-don't-care-about-wars-and-environment folk, biking is cheap. Driving costs approx 30cents to a mile, whereas biking is virtually free. Some initial investment and once in a while repairs.

It is good for health (will get you those washboard abs :D) as it burns about 10 cals/min. When there is no time to exercise, you know that you exercise for at least a few minutes a day on your commute. Then there is the community aspect. Less noise and smoke from traffic, reduced congestion on streets, pedestrian safety etc. It brings people together. You are no longer insulated from the world in your metal cage. It is good for your mental health as you don't get frustrated with traffic. Parking is usually not an issue.

You reduce parking requirements at shopping centers saving a few square feet from being paved. Imagine the amount of open space we would have if half the parking lots were converted to parks. Or tennis courts! Oh and I get gift certificates for biking to work. Sweet deal eh?

Some practical suggestions if you decide on commuting by bike. Panniers are very handy to avoid carrying backpacks that give you a sweaty back. If biking to work, you may have to take a change of clothes depending on weather, distance and fitness levels. Safety is paramount. I know many people fear getting hit by a car. I wouldn't say unjustified fears, but I think a little overblown. You should ride defensively. You will not win a battle with something 20 times your weight. So don't bother tempting fate. Wear a florescent vest and use front and rear lights to improve your visibility to drivers. Be predictable and try to anticipate the actions of drivers. Don't worry, it becomes second nature after a while. And always wear a helmet. Some practical info for new bikers can be found here.

Biking is a win win win win win situation. And I know that it is much easier to sit in your car and drive away, specially after a long workday. But how much good has come in this world because the easier path was taken? Get out there and put your foot down on a different pedal. Hop on that bike and rediscover the joy of biking. Remember the thrill, the exhilaration, the independence our bikes gave us as kids? Trust me, it is still the same.