I found Square while looking for a free credit card reader for my iPhone. After signing up, I found out that they have a referral program where you receive free processing fees on up to $1,000 in credit card transactions for the first 180 days. Click here to take advantage of this offer!
Square Point-of-Sale App is free as well. There is no sign-up cost or long-term contract. I can't wait to receiving it in the mail and trying it!