Square for iPhone and Android
Recently I have used a program called square on my iphone and I have to say, this is the fastest and easiest way of accepting credit cards. All you have to do is sign up, wait for your free card reader to come in the mail.. and swipe any credit card under the sun. The funds will automatically be deposited into your bank account!
Whats nice is there's no contract at all, and the only fee's are the ones coming out of the transaction.. say 2% or something.
If your running a small business and require charging credit cards, this is the best mobile charge system there is!