FlightGear Server Online Map
There are a number of real-time flight tracking maps in existence (checkout Flightradar24 or RadarVirtuel) but this is the first map I've seen that is tracking virtual planes.
FlightGear is an open source flight simulation game - and the game now has a map. The FlightGear Server Online Map is a real time flight tracking Google Map that shows where FlightGear pilots are flying online on the FlightGear Multiplayer Server.
The positions of aircraft of players currently playing FlightGear are shown in real-time on the map. The map includes a navaids search facility so that you can search for airports anywhere in the world and find out who is flying nearby.
It is possible to view all players currently online in the navigation box at the bottom of the map. If you select a pilot's check-box then the map will automatically centre on the chosen pilot and follow their progress in the game in real-time.