Via SlashDot, here’s a project from Potsdam University in which the clever boffins have built a user interface that requires only hand gestures as input:

We present Imaginary Interfaces, screen-less devices that allow users to perform spatial interaction with empty hands and without visual feedback. Unlike projection-based solutions, such as Sixth Sense, all “feedback” takes place in the user’s imagination. Users define the origin of an imaginary space by forming an L-shaped coordinate cross with their non-dominant hand. Users then point and draw with their dominant hand in the resulting space. The interaction is tracked by a tiny camera device clipped to the user’s clothing and pointed at the user’s hands.

A bit rough and ready, sure, but it’s early days. Bolt this onto AR (they both need similar face-mounted hardware, so convergence is pretty inevitable), and stuff gets weird real quick. Cities full of people wandering around, seemingly talking to themselves and waving their hands in gnomic gestures… it’d look like a city of mad magicians.

Or, y’know, like Burning Man or Glastonbury at 5am on a Saturday. 🙂