Google Earth Tracks Flights

Google Earth can give you the precise location of just about any commercial flight, almost in realtime. To get the flight information on just about any flight's progress, download Google Earth, then go to Aeroseek or FBOWeb to enter the carrier and flight number you're interested in. Once you've got it, click the Google Earth link to open that flight in Google Earth and see its exact location updated every few seconds.

Source (Wired Magazine)