Attention! To the 61% of Americans who carry a balance on their credit cards: the flurry of new cards that "reward" such behavior with cash back and other stay-in-debt incentives may cost you more in the long run. Providian is testing a Real Rewards card that, while promoting good habits like paying your bill on time, also gives 10 frequent-flyer-esque points for every $100 you carry over each month. American Express's Blue Cash card, which charges 8.99% to 13.99% interest, gives 5% cash back for revolving a balance on certain purchases. But you're better off with a low APR than with a rebate. That also holds for Bank of America's Money Return card, which annually rebates 10% of the interest you pay on rates as high as 16.99%. You can find cards with lower APRs (Wells Fargo offers 7.65%) on CardRate.com, where you can calculate how long you'll pay and how much interest if you pay down your bill with the monthly minimum only.