If you run a small firm in need of a quick and easy method for accepting credit card payments, look no further than the Square app. This app turns your iPad, iPhone or Android device into a register by plugging a swiping mechanism into the headphone jack. Once a payment has been processed, clients sign directly on your mobile device. Receipts can then either be sent via text or email, saving paper and time. Also, through Square Analytics, users can gain much needed business insights.
Cost: Free (there is a 2.75% charge per swipe)