Want to find every pizza place within a 15-mile radius? Where the dog parks are in a new town? The most central meeting place for your class, club or group of friends? The cheapest gas stations on a day-to-day basis? The location of convicted sex offenders in an area to which you may be considering moving? The applications, serendipitous and serious, seem to be infinite, as developers find ever more creative ways to add to and customize the satellite images and underlying API of Google Maps.

Written by Schuyler Erle and Rich Gibson, authors of the popular Mapping Hacks,...