Credit card terminals for iPhone

It's no secret that the iPhone is much more than just a smartphone. Apple has even started giving iPhones to Apple Store Concierge employees to schedule appointments and manage the store. The ability to complete mobile transactions with credit card terminals is a great use of the iPhone for employees on the go or companies that do home or office calls. Like most applications in the iTunes App Store, there is no shortage of alternatives available for you to try. 
Credit Card Terminal [iTunes Link] - $0.99
This app is pretty awesome. So awesome in fact, that it was featured internationally in an Apple commercial. The 99 cent application offers a (very) cheap alternative to expensive terminals and hardware. With a clean and easy to use interface, users can enter credit card information, complete transactions, and even view and refund past sales. The app also gives you the ability to collect customer information. The developer even offers telephone and email support and will walk you through setup.