Since many of my friends are engineers my community's approach to the environmental crisis is usually technical. Friends who drive hybrids, have installed solar power on their roofs, several who are totally self sustaining by installing solar power panels that sell back to the utilities etc.
But my approach has been a little different. I stopped eating red meat 15 months ago now after reading a particularly disturbing book about the abattoir practices in the U.S. Not an unusual decision but one that I think will become more and more common -- although I do realize humans like to eat meat (I myself fall off the wagon about 3 times a year).
The reason this trend will grow isn't that Americans suddenly start caring about eating animals with the intelligence of their young children, but because of the carbon footprint of the meat industry. It'll be because the meat industry produces more carbon emissions than the auto industry (cows belching -- amazing but true). For example, 4oz of steamed vegetables have a carbon footprint of 0.18lbs, 4 oz of pasta has 0.39 lbs and 4oz of steak has 10.5lbs. See the excellent Time article here.
Hybridization of cars is the easiest big impact change we can make, but it's a very expensive change. While we have a Prius for the family, I still drive a 7-year-old gas-guzzling Jaguar convertible and I expect I'll drive it into the ground since it's a very high carbon footprint to replace it with any new car -- and more cost effective to drive the car to the end of it's natural life (plus it's the most fun I've had behind the wheel of a car since I was dating).
If it's time for you to buy a car then buy a hybrid, but if you aren't in the market for a new car today the highest impact change you can make is to stop eating meat -- and it's good for you too.