This is a couple years old, but is just amazing. It is the results of a project to time lapse photograph a representation of Wi-Fi signals using a 4 meter lighted rod. A bank of 80 lights on the rod represent Wi-Fi signal strength of a particular Wi-Fi network around a building. Time lapse photos are taken and when it is put together you get the amazing effect demonstrated in the video.
Thanks to Yuri Chemerkin’s blog for the heads up on this.