You can use cashback rewards to pay down the balance of your credit card every month. While this lowers your balance, most credit card companies do not allow you to use the cash back rewards in place of a minimum payment though.
You can also receive a certain percentage of money back every time you shop at certain places such as grocery stores, entertainment venues, or restaurants. Some companies also run promos where they offer more cashback for a certain month if you make electronic or other high-dollar purchases.