try ps eye, eyetoy is the ps2 version which lacked a lot, and I mean a lot of features given it's release about 8 years ago I think it can get away with it. Natal wins though, if you said ps move my opinion would be for it, but the eye on its own, no chance.
ps eye:
- augmented reality which includes
-
- gender recognition
- facial recognition
- age recognition
- object recognition (patented well everyday items are patented)
- facial expression recognition (patented well laughter is patented)
- head tracking
- there is a mic but it's primary purpose was to help detect the position of the user, in my experience it isn't good at voice recognition, although that could be down to the software aswell
- allows for voip
- movement detection
there is more I'm just not thinking of it at the moment. oh and most of the augmented stuff is from what sony says is in its vision library with the exception of eyepet very few games use them.
natal (based on what MS has told us)
- augmented reality from what I have seen they also have a pretty descent library although they haven't demonstrated or shown age recognition. I don't see any reason why they can't do it though the facial expression and use of everyday items are patent protect so unless there is away round it. it includes gesture recognition something I am yet to see from the eye. (although move will likely do this)
- 3d depth tracking
- full body tracking
- mic, primarily designed as a command interface
- allows for voip
- one step up from the eye's movement detection instead of using the pixels, alone to determine movement, it will apparently use a ir bar to help detect movement in a given distance.
- area you have to be in will adjust depending on the size of the room.
- built in processor to do the calculations, freeing up the 360, processor.
- some motor things for tilting the camera and for fast zoom
again there is more probably a lot more with natal but this is just of the top of my head.
edit: when I say voip I mean video conferencing, any camera could probably allow this though