I went for a walk around Central Park last weekend as well, using this fun iApp by Bluebrain, called Central Park (Listen to the Light). "It uses a global positioning network to activate different themes as the listener wanders through the park. The app contains more than 400 tracks, each tied to a location. They were written to fit together harmonically like a sonic jigsaw puzzle."
I have to admit that I often find the GPS stuff creepy, but this was pretty cool. It was fascinating to hear the different musical themes layering and changing as I ventured from one area of the park to the next.
[Quote from the NYTimes, Photos by me]