* Eyeglasses that produce 3D images for the wearer
Aren't all eyeglasses supposed to do that? ^_^
A few years ago I was discussing speakers with Jim Thiel at Thiel Audio and he argued that speakers were better than headphones because speakers provide a natural 3-D effect as you turn your head. I said it would be interesting to reproduce the effect with a set of headphones that include a gyro to detect your head movements and adjust the audio signal to the headphones (phase, delay, amplitude, and perhaps frequency spectrum) to mimic what you'd hear if you were listening to speakers, or sitting at a concert.
The other day I was talking to his daughter and realized that you don't need a gyro or any new circuitry if you're listening in front of a PC with a webcam, because the webcam can track your face and calculate head position, and the audio would be adjusted with a plug-in in the music player. Someone is probably already doing it, at least with respect to enhancing the virtual world of 3-D goggles.