It's called Walk Score. I saw this on Yahoo's main page. Its a site where you can see how walkable some place is (more so for where you live/work). You basically enter an address and it calculates a score out of 100 of how walkable that address is. And based upon the score it will tell you if it's more car-dependable or a walker's paradise. The top three are: 1) San Francisco, CA, 2) New York, NY, and 3) Boston, MA.
I think it's pretty neat. Looking at the "Walkable Maps" they have for the most walkable cities, I noticed that the more car dependant areas are where fewer people lived (like parks) or developed neighborhoods (like in the suburbs of NYC).