Want to make it easy to give your cell phone number to someone? Carry this thing called @address. You put your phone number in it and then when you want to give your digits to someone you plug it into their cell phone and *poof* it registers your number in their phone. The make two models. On with a little light attached.
This is possible because there is a standard for it at least among certain phones. Unfortunately the standard is not 100% so not every phone is covered. I brings up the question though, if there is a bug and it erases your new acquaintance's phone list do you think they will still become your friend?