SquareUp is an awesome app/service that allows you to accept credit card payments directly through your iPhone or iPad. The fee is a modest 2.75% per swipe.
This could be a great solution for small vendors that don’t do a ton of transactions. There is no need for a merchant account, no monthly fees, and no setup costs. SquareUp will deposit your money directly into your account and they will even send you a free card reader. The card reader uses your audio jack and is about the size of a quarter. There is no limit to the number or amount of your transactions.
This is the most useful app/service for the “i” universe that I have found to date. It’s almost too easy.