In "Exploring Black Holes" by Taylor & Wheeler, project A is titled 'Global Positioning System', where they say locating your position accurately depends crucially on General Relativity.
GPS satellites are all tuned this way, and it has the desired effect.
However, for people implementing GPS receivers, the signal arrives already corrected for time dilation. So the people making that part of the system don't have to know about general relativity at all :)