"Program a map to display frequency of data exchange, every thousand megabytes a single pixel on a very large screen. Manhattan and Atlanta burn solid white. Then they start to pulse, the rate of traffic threatening to overload your simulation. Your map is about to go nova. Cool it down. Up your scale. Each pixel a million megabytes. At a hundred million megabytes per second, you begin to make out certain blocks in midtown Manhattan, outlines of hundred-year-old industrial parks ringing the old core of Atlanta..."
While wandering around downtown San Francisco a couple of weeks ago, I came across an art installation in the lobby of an office building that ostensibly displayed a realtime visualization of Internet traffic as a 3D map of the city. I'm not entirely sure that's accurate because that would require an immense amount of access to network infrastructure they probably don't own. My working hypothesis is that it's a visualization of activity of their customers run through a geoIP service with a fairly high degree of resolution (probably correlated against customer service records) and turned into a highly impressive animation. I didn't record any video footage, I just took a couple of pictures.
Here's a gallery of those pictures.