I found this interesting to see how GPS data can currently be easily collected, used and translated to the public. Similar to the OTTOCycle project done in the past.

http://gizmodo.com/strava-insights-lets-you-see-how-the-world-runs-and-cyc-1...

Strava tracks runs and rides and has collected an extraordinary amount of data, and sells it to city planners.

Their Insights http://insights.strava.com/ (http://insights.strava.com/) website lets you explore how some cities around the world runs and cycles.