Wired's Threat Level blog has a good story about a reformed conman who ratted out a young con artist who asked him for help in an ATM scheme. Instead, the older man gathered evidence and turned the guy over to authorities.
The ATM scheme is a variation that you've probably seen in the news over the past few years. One ATM manufacturer's admin codes were published on the Internet, so thieves were resetting machines to "think" that $10 bills were actually $1. Thus, any withdrawals would pay out at a 10-to-1 ratio. The manufacturer has updated its firmware, but a few ATM owners haven't reset their codes, so this stuff keeps happening.
Hat Tip: Many thanks, Tim P!