Geodetic computer for amateur radio use.
 
Converts Lat / Lon to Maidenhead Grid Square and reverse
Computes range in kilometers and great circle bearing between
QTH and remote site specified by Lat/Lon or Maidenhead Grid Square
Computes range in kilometers and great circle bearing between QTH and
a site selected from a database list for all known callsign prefixes
and their geographic position.  Geographic position is by major city.

WWW: http://www.w1hkj.com/#Geoid