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. - http://www.cockpitgps.com/
Pacific Coast Avionics. - Authorized avionics distributor of GPS, autopilot, and other aircraft instruments. - http://www.pacific-coast-avionics.com/
Fugro SeaSTAR - Differential GPS for oceangoing vessels. - http://www.fugroseastar.com/
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. - http://www.amazon.com/exec/obidos/ASIN/007011546X
Porcine Associates - Couplers that allow connection of hand-held or panel-mounted GPS receiver to autopilot. Follow a GPS course or hold a heading. - http://www.porcine.com/