I have a habit of doing a bit of personal data tracking- using various apps to keep track of what movies I've seen, what beverages I've enjoyed, and so on.
I've been using RunKeeper for some time to keep track of my runs, and in 2011 I decided to see if I couldn't use the GPS data to make a map of everywhere I ran. By exporting the GPS data from RunKeeper to a fusion table in Google Drive, I was able to make this pretty decent map:
Nathan Yau, with more skills than I, used public RunKeeper data to visualize where people run in 22 cities around the world. Also interesting and worth pointing out, that several of the maps (very noticeably NYC) show heavy running along marathon routes, which for the other 364 days a year may not see too much foot traffic.
Below are a selection of the 22 maps:
New York City:
Be sure to check out all 22 maps over at Flowing Data.