Elliot Seguin is a homebuilder, engineer, and test pilot. He is a member of the Society of Experimental Test Pilots and each year he competes at the Reno National Championship Air Races.
A technology developed by ham radio operators, called automatic position reporting system (APRS), coupled with low-cost GPS receivers, a decent antenna and the World Wide Web, have made it possible to track light-aircraft flights without incurring access or subscription fees. Yes, you'll need to get a Technician license for radio operators, but thats a minor obstacle if this system is something you want or need to use.