Unveiled at CES 2013, Displair is a gesture enabled water-based monitor. It works by having a touchscreen device connected to a projector, which puts the touchable image onto a continuous stream of vaporized water. It looks like it's primarily marketed as an advertising display unit or presentation device.
I was hesitant at first, thinking that it could get annoying if the display moves every time you put your hand though it, and wondering how much water you'd need, but it does look fun to play with. Also the website says it moisturises air and benefits the skin, no other monitors seem to do that!