I've said it before but I'll say it again: land use patterns that allow for easy non-car accessibility on common trips are far more impactful for the environment than other so-called "green" practices. That most Americans don't think twice about firing up a two-ton steel box, waiting for it to heat up, and then driving it all of five minutes to pick up a gallon of milk or drop off dry-cleaning is disastrous for our ecological balance, to say nothing of the economic and geo-political ramifications of our oil consumption.
This is one of the reasons I've grown quite fond of living where we live. Consider how much we access often that is within a mile of our house, or an easy 15-minute walk:
* My place of employment for 15 out of the 16 years I've had a job.
* Amy's place of employment for 5 out of the 14 years she's had a job.
* An Ivy League school where we've gotten a combined two undergrad and two grad degrees.
* Where Jada has gone to school 5 out of 6 years.
* Where Aaron has gone to school 3 out of 4 years.
* Where we have been going to church the last 15 years.
* Where we all exercise at the YMCA.
* And, of course, three subway stops and countless trolley and bus stops to get us to places further away than walking distance.
This list doesn't include the manifold retail, food, recreational, and other amenities we commonly access. Live, work, play, and worship, all without a car. That's why inner city Philadelphia, which you may instinctively associate with grime, is actually quite green.