Amazon Prime Air, not to be confused with Amazon Prime, will use octo-copter drones to deliver your amazon purchases under 5 pounds to your doorstep in under 30 minutes. At least that is the plan for now. The technology is still in development and Amazon is waiting to pass FAA rules and regulations (for airspace I would assume). This technology won’t be available before year 2015 at the earliest and the FAA won’t certify drones for commercial uses until year 2020.
Either way, with the amount of people buying from Amazon, be prepared to see these drones flying everywhere all the time.