Taiwanese startup AirSig has come up with one of the more novel password replacement technologies that I've seen. It identifies you by the unique way you wave things around in the air. If the thing you're waving happens to be an AirSig enabled smartphone, then all you have to do is "write" the name in the air of whatever it is you want to access, and you're in. For example, for Facebook you'd write "FB". Kind of like air guitar, only you're writing instead of rocking it.
AirSig's technology, Air Signature, uses g-sensors in the smartphone's onboard gyroscope to identify a user's personal shaking pattern.
Consumer takeup will be determined in large part by how many people aren't too embarassed to be seen, seemingly randomly, waving their arms around in the air as they go about their day. Count me out there, but I guess given the number of folks who think nothing of walking around while looking down at their phones, AirSig could have an audience of millions. Foxconn thinks so, and just invested $2 million in the company.
Here's a promotional video for Air Signature: