While post offices in the U.S. are closing, in Japan a website called Post Map is mapping the locations of post boxes and addressing issues like post office closures and the privatisation of postal services.
Google Maps is used to provide a crowd-sourced map of post box locations. Citizens can find their nearest post boxes by submitting locations and photographs to the map. If you select a post box then the map sidebar shows you how far it is to the nearest alternative post boxes. This would be good for people new to a neighborhood and for getting up-to-date locations of post boxes as there become fewer of them available.