Stumbled across a new (to me!) feature at Walkscore.com...
Maps that show the most walkable areas of the top 40 metro areas in the US. VERY cool to check out!
There's also a list of neighborhoods from the top 40 metro areas listed in order of walkability.... not quite as useful unless you're wide open about where in the country you're living or moving to, but still interesting.
Oh, and they also added instructions for adding new businesses, etc and removing outdated info to make the site more accurate.