Coming soon is a new "broadcast" RFID technology called Near Field Communication. It will enable you to buy things with your cell phone. http://electronics.howstuffworks.com/nfc-phone.htm What if stores decided to require you to have a device like this to enter their store ? If you get rid of paper money, and you need to have a cell phone to buy anything ... they could say ... we only let people in the store with cell phones. What if the cell phone broadcasted your ID and that stores prevented you from entering unless your ID was received by a device at the store entrance.