Crows are pretty smart

Crows learn very quickly, most people knows this. Here's a guy that built a vending machine, conditioned the crows with peanuts and pennies so that they learn that putting a penny in the slot gets them a peanut. Then more conditioning and they figure out to look for dropped pennies all over so that they can get thier peanuts. Crows get food, guy gets money, neat little transaction.

Realy amazing, with this taken further, crows could be taught to clean up garbage of the street to get thier food for example.

http://www.mentalfloss.com/blogs/archives/15322