Recently, Chad steered me towards Mapnificent - an engaging tool that dynamically shows you "areas you can reach with public transport in a given time." If you live in an area without much public transport, like Nashville, it may not be all that handy but somewhere like San Francisco, New York or Portland reveals a lot of very useful information. At the very least, if you're considering moving it could be a phenomenal tool to determine where your best neighborhood to check out should be.