I turned my quadcopter into a Ghostcopter for Halloween! Pretty easy with some cheese cloth, foam ball, and LED's.
My setup:
SK450 Frame - http://www.hobbyking.com/hobbyking/store/__24291__Hobbyking_SK450_Glass_Fiber_Quadcopter_Frame_450mm.html
DJI Naza M Lite with GPS Unit --
http://www.uavproducts.com/product.php?id_product=21
NTM 28-26 1000 kv motors - http://www.hobbyking.com/hobbyking/store/uh_viewItem.asp?idProduct=21478
Turnigy ESC's 30 Amp --
http://www.hobbyking.com/hobbyking/store/__2164__TURNIGY_Plush_30amp_Speed_Controller.html
Battery is 3000mAh 40C-
http://www.hobbyking.com/hobbyking/store/uh_viewItem.asp?idProduct=9952
Basic Props-
http://www.hobbyking.com/hobbyking/store/uh_viewItem.asp?idProduct=22438
http://www.hobbyking.com/hobbyking/store/uh_viewItem.asp?idProduct=22439
PCB Main Frame --
http://www.hobbyking.com/hobbyking/store/uh_viewItem.asp?idProduct=25488
Green Replacement Arms-
http://www.hobbyking.com/hobbyking/store/uh_viewItem.asp?idProduct=25566