The FAA now requires all drones (including those used by modelers and hobbyists) to be registered starting 12/21/15 and must be done by 2/19/16.
Unmanned aircraft weighing less than 55 pounds and more than 0.55 pounds (250 grams) on takeoff, including everything that is on board or otherwise attached to the aircraft and operated outdoors in the national airspace system must register. These aircraft may be registered under the new web-based registration system.
For more information, click here: http://www.faa.gov/uas/registration/faqs/
https://youtu.be/0ql5IMpmhnc
For individuals who want a high quality, easy-to-install, long-lasting decal that can be customized to match their UAV, RCDecals.com offers 3M professional UAV registration decals delivered to your door.
These decals are universal so they can be used on the following plus any other UAS/Drone: