Recently, an acquaintance asked me how to measure the walkability of a place he was visiting.
I could have told him to just look at Walkscore (www.walkscore.com). Walkscore assigns scores to places based on their proximity to a wide variety of destinations. So if a place has a high walkscore AND a walkable street design (e.g. narrow streets, a grid system, etc.) it is probably pretty walkable.