The reason I ask, is if I knew what else used them, I would have more places to look for deals, and maybe even find them locally. As it is, I know of nothing else that uses them.
18650s and 14500 are usually not used as loose cells. They are used in battery packs such as laptop battery, video camera. You will find that most laptop manufacturers like to use 18650s and 17670s.
Comcast used to send out an all-in-one cable modem/voice over IP device that uses a backup battery pack. I got four unprotected 18650 cells out of that. It's made by Arris and the model # is: TM502G.