Not sure if this is still the case, but in the past the FirstUSA/BankOne/Chase United Airlines Gold Visa awarded miles (at the rate of 1/2 mile per dollar) for using their "convenience checks". Some months they would send special convenience checks with the 3% fee waived and you could write the check to yourself, deposit it in your bank account and then immediately make an online payment the day the charge posted to your Visa account. If you timed it just right, there was no interest so the miles were effectively free. I believe that they had a 10,000 mile annual limit per card on the miles you could earn this way.