Tokyo Bay Monster-fashion (sans holographic video monster), a designer named Julius Popp has created a system of displaying moving text and images using falling drops of water, thus creating a kind of virtual billboard that appears to be hovering in mid-air. The system -- called AquaScript -- works by utilizing magnet-valves which expel single drops of water on demand; proprietary software syncs the valves into a "freely definable bitmap-muster" which produces blocks of images with the falling liquid. Check the video after the break and see the wetworks in action.
Update: According to the flurry of activity in comments, Jeep has been up to these shenanigans for quite some time, though it appears they're using a system designed independently of this one... which kind of makes Mr. Popp's work just slightly less exciting. Thanks guys!