I've written about the ATM scam before, but as the scam seems to be spreading, it bears repeating. Victims of the ATM scam can find their accounts drained dry before they even know their account information has been stolen.
The scam works this way: the crook places a cap, made to look like a part of the machine, over the card slot of the ATM . This cap reads the magnetically encoded info as the card passed through and into the ATM. A pinhole camera is placed so as to record the PIN as the victim keys it in. The victim gets his cash, card and receipt, as usual. After he leaves, the crook retrieves the cap and camera. Using a mag card writer, he creates a duplicate card and, with the PIN, begins to use the card as fast as possible.
This video does a great job of showing in detail how the scam works, and how to avoid it. The number 1 tip: ALWAYS SHIELD THE KEYPAD WHEN ENTERING YOUR PIN. Follow the same advice in stores, too; you don't want to temp a crook to snatch your purse or pick your pocket by revealing your PIN to them. If you think your PIN is compromised, change it.