Want to accept card payments with no merchant account, monthly fees, or hidden costs? Then SquareUp is for you. Your business in real time! Track sales, tips, tax and sendreceipts electronically. They handle security so you can focus on your business.
Another service that offers credit card payment on the iPhone or iPad is Mophie.Mophie charges you for the device and also charges you a monthly service fee where as SquareUp sends you the device for free and has no monthly service fee but takes a percentage of your transactions. You can review both devices here Mophie and SquareUp