A three-dimensional projection display is always one of those features teased in the least believable "next iPhone" leaks, but it turns out your phone already has one, sort of. With a couple of prisms and an optical illusion called "pepper's ghost", just about any screen can summon up 3D graphics.
This little trick was devised by Japanese designer Yuri Endo for his thesis project. Called the "Luminogeist", the set of four prisms can effectively take images off the screen of an iPhone (or any device, really), bounce them around, and merge them to generate what appears to be a tiny, floating animation.
There's not much of a practical purpose for it other than being awesome, but honestly, what better reason is there than awesome? It's just too bad these sets aren't for sale. At least not yet. Hint hint nudge nudge.