Originally Posted by m4a1mustang

There's another fun trick if you want free airline tickets... Well, the US Mint put an end to it in July of this year, but basically you would order as many US $1 coins as you could at a time (I think it was $5,000) and the Mint would do free shipping.

Order them on your credit card.

Take delivery. Haul them to the bank. Deposit. Pay off your card. Collect airline miles.

It was riskless arbitrage. As long as you didn't incur any interest charges, you got free airline miles.