Flight Tracker from Aireon.
From AvWeb:
Beginning in 2017 any aircraft, GA included, with ADS-B out transmitting at 1090 MHz will be automatically tracked and the precise location of its last transmission anywhere on earth recorded. At last week's ICAO High Level Safety Conference, Aireon LLC, which is launching the first space based global air surveillance system, announced that the headquarters for its Aircraft Locating and Emergency Response Tracking (Aireon Alert) will be at the Irish Aviation Authority's North Atlantic operations center in Ballygirreen on the west coast of Ireland. Once the Iridium constellation of satellites carrying the ADS-B receivers is complete, any airline, search and rescue organization or any other group needing "last known" information on a flight can get it for free from Aireon. VP of marketing Cyriel Kronenburg told AVweb it will work for all aircraft equipped with 1090 MHz ADS-B and the mystery of Malaysian MH370, a Boeing 777 which hasn't been found since it disappeared a year ago, prompted the ALERT service.