It's not always easy to know if your affinity card's a turkey (unless it's the one offered by the National Wild Turkey Federation). The right card for you will depend on several considerations, such as how much you want to see go to the charity, the card's annual interest rate, and your spending and payment habits. If you pay off your balance in full each month, the annual interest rate needn't concern you too much. But if you often carry a balance, you'll probably be better off getting a card with a lower interest rate and writing a check to your cause. Here's a sample of affinity cards, in alphabetical order. None has an annual fee.