>My American aunt gave me a $2 bill, in a wee presentation cardboard wallet, when I was a kid, saying "Take care of this. These are rare and it might be worth something in the future." I think I still have it somewhere. What's the score? Are they rare? Was she BSing me?

Yes, they're rare. Nobody uses them regularly. We have a small pile of them here that someone gave one of the kids for a gift, but otherwise, I haven't seen any in years and years.

Tamar