theAirDB looks interesting; it shows which airlines serve the airport of interest. This could be useful for planning side trips, or for positioning purposes. Alas it wasn't completely accurate as they don't seem to follow all airlines (e.g. Jet Airways isn't covered at present); maybe this is just a matter of time.
Thanks for theairdb link. Doesn't seem to be too accurate.
Eg1 Air NZ has APW as a hub and is missing NLK, VLI, NOU, ADL, plus 20 of the 26 domestic airports served!
Eg2 QF includes codeshare & other airports not served (eg PPT, FCO, BUD, PRG), lists ZQN as a hub (along with other spurious hubs eg NAN not even served by QF), and missing airports such as JFK.