Handheld GPS in the Cockpit http://www.cockpitgps.com/
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.
Porcine Associates http://www.porcine.com/
Couplers that allow connection of hand-held or panel-mounted GPS receiver to autopilot. Follow a GPS course or hold a heading.