At one of my favorite local coffee shops, I've noticed they have a creative take on generating tips. I'm sure this is used elsewhere as well, but it's the first time I've come across it.

There are two baskets by the register, with a rotating sign above that asks a question. Today it was: "Should Obama pick Hillary as Vice President?" Throw your tip in the appropriate basket, and we get an instant, visible poll as a byproduct of giving your barista a little extra change. Some questions generate a more noticeable swing in basket preference (sorry, Hillary), while others are just fun throwaways.

A small reward for participation. I'm sure there's a parallel here with social web interaction, but I'll let Josh or someone else who's hot on this topic decipher it.