Some friends of mine just got back from a cruise last week and shared with me their mileage "scheme".

When you get onboard you are given an id card that is linked to a credit that you give the cruise line before you board. Any charges that are accrued onboard from this ID are charged then to the credit card at the end of the cruise.

What they decided to do was to link their US Airways Dividend Miles credit card to their ID and everyday would withdraw cash from casino via their ID card. At the end of the cruise they had amassed a stack of cash and miles. Once they got home, they deposited the cash into the bank (to pay their credit card bill) and used the miles to top off their account.

I would feel uneasy hording such sums of cash but I guess if you feel comfortable enough, its a good way to get some extra miles.