zip-center accepts n ZIP codes on the command line. It converts these ZIP codes to latitude and longitude, averages them separately, finds a ZIP code whose center is nearest the lat/lon center point, and computes the distance of each input zip code from the resulting centrally-located zip code in miles (taking into account the variable width of longitudinal differences). This allows a caller of the script to do things like pick a centrally-located venue for a meeting given the ZIP codes of the prospective attendees.
