The Bus or Subway Battle Map

I always find interactive isochrone maps very impressive. They are a great demonstration of how digital maps can process and visualize large amounts of data on the fly. Real-estate isochrone maps are particularly useful, allowing you to search for properties within a defined commuting time from your place of work.

Another useful use of isochrone maps is for comparing the travel times between different modes of transport. Transit Battle NYC is a great example of using isochrone mapping to show where in New York you should catch the bus and when you should use the subway instead.

Drag the marker to a location on this map of New York and you can instantly view an overlay visualizing where you can travel to fastest by bus and where you can travel fastest to by subway. The map uses data from the MTA's GTFS feeds for the transit time data which is then processed with OpenTripPlanner.