i carry a few credit cards, but my primary one is an amex cash rebate card. with it, i get a graduated cash back reward that goes from 0.25% to 1.5% (when i spend more than $5,000 in a year). i am thinking about switching over to the amex blue cash card. it pays 0.5% to 1% until you spend $6,500 in a year and then it bumps that up to 1.5%. then it bumps the reward to 5% on purchases at gas stations, drugstores, and supermarkets. it's got no annual fee and a 0% APR for the first 15 months.
sounds like a decent way to 'save' some money on money that i'm going to be spending anyway.