The following files are georeferenced jpegs, for use
with globalmapper (www.globalmapper.com)

A complete set of files consists of :

image.jpg      =     jpeg of area of interest
image.JGW    =     world file for image.jpg
image.prj       =     projection file for image.jpg 

If loaded into globalmapper, these imagery files are properly
located on the world grid. Globalmapper can further be used
with a gps to plot positions in real time using the above 
imagery.