Aviator's Guide to GPS: Get a feel for using digital readout and moving-map GPS receivers with this book's unique, fully illustrated examples that is devoted solely to GPS navigation.
Fugro SeaSTAR: Differential GPS for oceangoing vessels.
Handheld GPS in the Cockpit: Information on using hand held GPS units in the cockpit addressing issues such as navigation, aviation vs. non-aviation units, where to get waypoints and other relevant topics.
Pacific Coast Avionics.: Authorized avionics distributor of GPS, autopilot, and other aircraft instruments.
Porcine Associates: Couplers that allow connection of hand-held or panel-mounted GPS receiver to autopilot. Follow a GPS course or hold a heading.