Equipment Manufacturers

Brunton - Maker of Atlas GPS receiver
Garmin - Offers broad line of GPS receivers for recreational, marine, and aircraft applications
Lowrance - Maker of the IFinder line of GPS receivers
Magellan - Offers broad range of GPS receivers
Cobra - GPS receivers for recreational use.

Maps

TopoZone - Online interactive topo maps of the entire US
National Geographic Topo! - Makers of popular TOPO! software for use on a personal computer
Maptech - Makers of mapping software including Terrain Navigator Pro.
US Geological Survey - This link gets you to their topographic map home page

General GPS Information

gpsinformation.net - Excellent web site with information on all aspects of GPS
GPS Nuts - Another good web site for learning the basics of GPS
GPS2CAD.com - Software that allows you to transfer data from consumer GPS to CAD programs

Book Publishing Resources

Para Publishing - Resources for the small publisher
PMA - Formerly Publishers Marketing Association, a publishing industry trade association
Greg Hinch (cover & web designs)