Not in and of themselves and certainly not until they have reached a scale that allow serious criminals to hide in plain sight. The problem for blackmailers has always been one of finally getting your hands on the money without discovery.

The closest I have seen someone come to doing this is the guy who had the victim deposit money in their ATM -accessible account and then told them to scan the magstip data from the ATM card and send it to him. This card cloning approach is similar to what some card thieves use. Only insecure communication channels revealed his whereabouts and led to his arrest. Otherwise, use of the magstrip is inspired and sure to be successfully repeated in the future.

For the less criminally minded this magstip ploy can enable pseudo anonymous ATM card acquisition and use from cooperating bank account/card suppliers, especially those offering e-gold and other e-currency funding. If the card agent is inclined to send the magstip data to the client in an encrypted form it could offer substantial privacy. Do banking regulations need physical delivery of cards by agents in order to adhere to know-your-customer requirements? If not, then simply 'borrowing' the identity of someone else may suffice for establishing and using accounts.

steve