North Korea's Human Jumbotron.

Every year, North Korea organizes the Grand Mass Gymnastics and Artistic Performance Arirang (better known as The Mass Games) to celebrate the late Kim Il-sung's birthday. One of the highlights of the events is the "human jumbotron" composed of up to 15,000 children flipping through colored placards. Hit play, or go to the http://video.google.com/videoplay?docid=5336239832047733845&q=north+korea+mass+games&total=92&start=0&num=10&so=0&type=search&plindex=2 [YouTube] to view.

For those curious or skeptical, here is another video showing how they created the Jumbotron effect (from the documentary "A state of mind" - via an anonymous comment to South Korea's human LCD)