The most used website for urban navigation in the United States, HopStop (http://www.HopStop.com) provides door-to-door mass transit directions and maps withing several large metropolitan markets, including Atlanta, Baltimore, Boston, Chicago, London, New York, Paris, Philadelphia, Providence, San Francisco, and Washington, D.C. Take HopStop anywhere you go with our free iPhone, Android and BlackBerry mobile apps: http://www.hopstop.com/mobile