http://www.flightradar24.com/ is an aircraft tracking website that plots aircraft on a map using the aircraft's own data that is transmitted as it flys. This is called ADS-B which is a form of ACARs. All parts of the world are covered by enthusiasts that download their data to a central server which is then plotted.
Aircraft can be filtered ,there track shown and aicraft details shown.
Very nice web page.
