A team of Japanese scientists have refined the art of creating images in mid-air --- Holography. By focusing an IR laser to a tiny patch of air, air molecules are heated to become glowing plasma. Like your old CRT television, an image is formed by scanning the laser's focus through the air, one point at a time. As the laser is only active for femtoseconds (read: a very, very short period of time), the powerful laser is rendered harmless and the image can be touched.
Earlier demonstrations can be found here:
