Via Brad Delong, an article about a guy who makes a living selling donuts and bagels on the honor principle. Take an item, drop some money in the box. There are some very interesting regularities in who cheats and when they cheat. Who cheats is basically in line with my expectations based on dealing with people in different lines of work. If it confirms my prejudices, it must be true :-)

Anyway, grab a donut, drop your coins in the slot, and read the article.