CoordTrans - Convert geographic coordinates between UTM, WGS84, NAD83, NAD27 and other national grids.
Decimaldegrees - Investigation of and experimentation with various GIS technologies, and the Internet. Latitude, longitude conversion and geocoding tools.
SeisSoft - Producers of projection and datum transform software.
ZipMath - World database with latitude and longitude coordinates. Includes formula for calculating the distance between any two world cities.
