This surprised me: a few weeks back I took $50 out of the ATM at my bank and it coughed over three $20 bills. The first surprise came when I got this compunction to take the extra to the teller (I still can't believe I did that) but then he talks to his supervisor and they tell me thay have no mechanism for putting the extra $10 back into the system, so ... enjoy. I bet they'd have found a way if it had slipped me an extra grand. I bet I'd have thought longer about returning it, too ;o)