Mapnificent may be the coolest website I've come across in a while. For selected cities, it allows you to see how far you can get on public transportation from a specific address. You can adjust the time. The image above is the default in Dallas with a radius of 30 minutes. Of course, the site has disclaimers that there are no warranties—so don't be upset if it takes longer to get someplace in your area! But it's a great tool when looking at places to live and to explore. Although it's still in Beta version, Mapnificent has cities around the world and is adding more frequently. If nothing else, it's an amusing time-waster. Enjoy!