Amazon has a private label credit card called Amazon Rewards. If you are an Amazon Prime customer, when you make a purchase you offered {$1.00} in credit if you accept normal shipping rather than Prime Shipping ( two-day ). But, Amazon does not offer its customers an easy way to figure out how much credit they have accumulated and when these credits expire. As far as I can tell, the only information about credits presented to customers takes place through email. Amazon should provide an easy accounting of credits on its website. 
