OK, I don’t know where I’d put it or exactly what I’d do with it yet, but I want one of these. FogScreen is a large wall of fog kept in a thin sheet using laminar flow, then used as a projector screen. That part has been around for a while, but they’ve recently added the ability to “write” on the screen like some wizard writing runes in the air, using the same ultrasound-tracked pens used in virtual-whiteboard systems. Check out their video.