Hopstop is an awesome site that gives you detailed directions for getting around via public transportation. This is an invaluable tool for city dwellers that eliminates the need to sift through confusing maps. Unfortunately, Hopstop is currently only available for New York City, Boston, Chicago, Washington DC and San Francisco. But for those lucky city dwellers living in those areas, HopStop is now offering two other ways to use their free service for times when you don’t have internet access. One option is to SMS or email Hopstop using your PDA and you’ll receive a reply with subway directions. The second option is to call HopStop and speak your address and HopStop will then send the directions to your cell phone. The only catch is that you must register first to take advantage of these mobile services. But otherwise Hopstop.com itself doesn’t require registration to use.