[jodrellblank]

What the heck is my brain doing in my free time?!

If you're bored... people ask for a touch sensitive rear surface - how about using the rear camera for gesture control?

Wave your finger in front of it to scroll, that kind of thing.

Also, some acoustic gesture recognition would be good to pick up one/two/three fingernail taps on the back.

[kenjackson]

Apple's already patented it. I don't want to get sued into oblivion. :-)

http://www.addictivetips.com/mobile/iphone-control-through-c...

[jodrellblank]

That's annoying, but it only seems to cover tap detection by accelerometer where I was thinking of tap detection by audio click, which definitely seems plausible from a quick test of the sound recorder.

Also it only covers finger swipe detection/direction determining, where I was also imagining gestures from holding fingers a few centimeters away, such as scissoring two fingers, thumb/finger flick, two finger scroll movement, two fingertips touching, etc. A quick test with the iPhone camera suggests that might have to be too carefully positioned to be practical, but should be possible at some level.