I recently signed up for ExpressPay from American Express. ExpressPay relies on innovative technology called Radio Frequency Identification. To use it, hold your Card or key fob up to the reader located by the checkout to pay for your purchases. Radio signals from the reader capture information on your Card or key fob and authenticate the transaction. Exxon/Mobil Speedpass, which came out a few years ago, works similar.
At this time, there aren't that many businesses that accept the ExpressPay service. However, the cafeteria at work is one place that does and I received a $5 credit for signing up. Nothing beats a free lunch! Plus, ExpressPay will save time during checkout and prevent me from going to the ATM to get money for lunch.