This CreditCardWatcher blog post has a useful review of several cash back credit cards. Its two top picks are Priceline Rewards Visa and US Bank Cash+ Visa Signature Card. The Priceline Rewards Visa earns an untiered, uncapped 2% rebate on all purchases. The post gives an honorable mention to the Fidelity Investment Rewards American Express Card. Like the Priceline card, it also offers an untiered, uncapped 2% rebate on all purchases. However, since it's Amex, it doesn't have the wide acceptance of a Visa or MasterCard.