New York's Citi Bike scheme has been up and running for a couple of months now—which means there's a glut of data available to analyze. This interactive New Yorker viz shows how the bikes were used every 15 minutes between June 8th and July 8th.
It does look a little chaotic, but there are some interesting trends in there. You can make out stacks of commuters in the week—especially toward the Financial District—and longer slower journeys at the weekends. Most fun, though, as Verge points out, is the mass migration westward before the July 4th fireworks on the Hudson. What else can you see?