If EF had a way to search for flights scheduled to arrive at a particular gate, that could be used to find the backing flight. (You'd do a flight status query on your departing flight, see its gate assignment, then do a query to find the flights scheduled to land at that gate.)

If you're flying AA, AA.com's flight status and gates and times forms have a button to show the incoming flight information. Very handy to know if your flight will board early or late.