The Tour De France stationary exercise bike from ProForm uses Google Maps to simulate any public street ride in the world, simulating the resistance (and tilt) of elevation changes as well as the wind resistance created by the rider's motion. That has to be one of the best "non-mapping" applications of Google Maps data that I've ever heard of.
When is someone going to come out with a treadmill that does the same? You could walk into a hotel somewhere and run the exact same course as at home. Or you could practice running the New York marathon from anywhere, with every hill included.