Here is a pretty neat video from Foursquare that depicts how its New York City and Tokyo-based users' check-ins light up their cities throughout the course of a day. Though the video is just a minute long, the data was compiled over a year. As Foursquare notes, this data helps show how "every city around the world pulses with activity around places every hour of every day." And, most interestingly, the lights are color-coded so it's easy to see when New Yorkers are grabbing breakfast or whiling their evenings away in bars and nightclubs. Here, go watch.
Video: Foursquare check-ins show the pulse of New York City and Tokyo