If you're distant enough / the people are sitting close enough, you can stereogram two people's faces together. You usually only get fleeting moments of crispness when their heads are aligned correctly though.
Yep! If I knew someone IRL who was into this kind of stuff, I'd really love to experiment with this sort of thing and mirrors. Arrange so that you can stereogram your conversation partner's face with a mirror image of your own face (and that he can do the same with your face and a mirror image of his face). If anyone's in NYC and interested in these sorts of things, my email is in my HN profile "about".