My dad takes clients out to lunch a few times a week. He always tips the server with $2 bills. Every server on his side of town remembers him, and his favorite drinks, meals, etc. (and really impresses the clients!)
When I used to work as a valet it was a big deal every time we got a $2 bill in tip. When we were splitting the tip we would always ask if any of the new guys had never gotten one before and make sure they got one.
There was a factory in a town somewhere that paid all its workers' bonuses in $2 bills so that the town could see the effect that the factory had on the local economy.
