Enter ArrivedOK, which automatically notifies people when you land. Just sign up for the free service, perform a few setup tasks, and hit the friendly skies. Watch this video to see how how ArrivedOK works:
It would be awesome to see this kind of functionality integrated with, say, TripIt, so you don't have to manually enter your trip details.
Until then, ArriveOK is one decidedly handy travel tool, as it saves you having to jump through countless communication hoops every time you reach your destination.
Speaking of flights: