Punch Drunk loophole

"At least several hundred mile-junkies discovered that a free shipping offer on presidential and Native American $1 coins, sold at face value by the U.S. Mint, amounted to printing free frequent-flier miles. Mileage lovers ordered more than $1 million in coins until the Mint started identifying them and cutting them off.
Coin buyers charged the purchases, sold in boxes of 250 coins, to a credit card that offers frequent-flier mile awards, then took the shipments straight to the bank. They then used the coins they deposited to pay their credit-card bills. Their only cost: the car trip to make the deposit." found on the Wall Street Journal