How about retrofitting DNS to do this? Encode a persons GPS coordinates in a TXT record. Now instead of writing my address on an envelope, I write me.example.com. The mailman/post office can then look up someone's coordinates via a DNS query. The benefit of this is that when I move, I can simply update my DNS entry. I could either host my own address or 3rd party could. Local government could grid up their own regions and assign address to fixed locations. You could choose to CNAME your address to the government allocated address or use the government issued one for the plot.