We've long known about Arthur C. Clarke's prediction way back in 1945 that artificial satellites placed in a geostationary orbit could be used to relay radio signals around the world—but we has no idea that 11 years later, he revisited his famous essay "Extra-Terrestrial Relays—Can Rocket Stations Give Worldwide Radio Coverage?" to predict the GPS ... and more.
In a 1956 letter to Andrew Haley of the American Rocket Society, Clarke expanded on his earlier theories and wrote:
" ... the three stations in the 24-hour orbit could provide not only an interference and censorship-free global TV service for the same power as a single modern transmitter, but could also make possible a position-finding grid whereby anyone on earth could locate himself by means of a couple of dials on an instrument about the size of a watch."
Clarke went on to say that:
" ... no-one on the planet need ever get lost or become out of touch with the community, unless he wanted to be. I'm still thinking about the social consequences of this!"
So are we, Sir Arthur. So are we!