Square allows small businesses and individuals to collect credit card payments. It works by using a small hardware dongle that connects to the headphone jack of a mobile device. The card is then swiped through the device and payments can be collected on the spot. It works on iPhone, iPad, and Android phones. Customers sign the device and a receipt is e-mailed to customer.
Square charges 2.75% of every transaction, but there are no monthly or additional fees. They are now processing more than $1,000,000 in transactions a day.
Square Home Page: https://squareup.com/