I know it's been done to death, but I was at this coffee place and half the people weren't just showing stuff on their phones to their friends, they were *only* looking at their phones and nothing more.
At least turn the screen to the other person and show them a nude picture or a cat picture :P
I like sharing-tech, but the kind that will (for example) allow me to flick a picture on my screen towards a friend's immediate location, the phone will use blutooth to see which friends are in the visinity and then calculate which phone of those is closer to the direction i flicked the image to. And then send it to their screen...
(Yeah I'm aware of how ironic it is to post this kind of a PSA thing in a blog thingy.)