"In the summer, we had one customer use Power Perks at a home improvement store to finish his deck, and then he used the cash back to buy all his Christmas gifts that year," O'Malley says.

At Ally Financial, customers earn cash rebates or Ally Perks, by making purchases -- with and without a PIN -- with their debit card at a specific retailer. Ally used its Facebook page to request recommendations from its customers for merchants they would like to see included in the program. Some of the retailers that have offered Ally Perks include 1-800-Flowers.com, iTunes, PetSmart online and Omaha Steaks online.

"We rotate the merchants every two to four weeks with different offers, which range from 10 percent to more than 50 percent back as a cash rebate that is automatically deposited in the customer's account," says Beth Coggins, spokeswoman for Ally Financial in Detroit.

PerkStreet has been letting its customers select their own categories for earning extra debit card rewards by participating in surveys and making recommendations through social media.

"Recently our customers have requested and received Power Perks from Old Navy, movie theaters, amusement parks, ice cream stores and online bookstores like Chegg.com," O'Malley says. "On the redemption side, they can just keep the cash, or they can use it for prepaid credit cards to use anyplace or on gift cards for a variety of retailers."