Until we can activate our computers by simply addressing them (think more "Scotty to the Enterprise computer" than "Samuel L Jackson to Siri"), we'll just have to rely on MIT Media Lab's new floating-point system to talk to the machines.
Like those animated photographs from Harry Potter, the ZeroN system is designed to provide a lasting, kinetic memory of your interaction with it. The system utilises a moving stack of powerful, computer controlled magnets to levitate a steel sphere as well as an optical tracking system and a projector.
Both the user and the computer can communicate by moving a steel ball within a three-dimensional space. The system will track the ball as the user moves it within the space — essentially programming a flight path — and then "play back" ball's exact trajectory indefinitely by manipulating the intensity of the magnets' repulsion. The projecter is used to display images onto the the floating sphere.
You could, for example, recreate the Moon's orbit around the Earth by placing a small globe on the device, programming the sphere to circle it, then projecting an image of the moon onto it. Just don't wear a watch near it. Or earrings.