If you haven't seen this already it's a video made in South Korea for Samsung featuring 1,152 people coordinating their moves to make images (like a monster LCD screen). They're not using cards, but clothes with different colors to make the changes. It's pretty mesmerizing, particularly if you've been doing drugs. In addition, at 1:05 in the video a cameraman almost gets trampled on the left side of the screen. Sweet. I particularly like the dancer they make at the 3:00 mark -- I think I saw her muff.
Youtube [thanks to ultra-cool tz for the tip]