For many years now I have used Wikipedia as a great guide for all the airline service into each individual airport as each airport article has a usually complete and up to date list of airlines and destinations. In my travels round the internet I have never come across anything similar. Is Wikipedia the only site to have amassed a 'database' of every airline service out of every airport? Seems something that aviation sites may wish to start building.
I use them as well all the time. Whenever someone asks whether airline X flies to airport Y, I direct them to the Wiki article. There's a good number of aviation enthusiasts (like myself) on there.
The main reason for that is usually each city has one or several "fanboys" or wiki-geeks that keep that info very current. It is easy for them because it is a hobby and they have pride in their city.
For a large website like Airliners.net to do it, accurately, you would need a fairly large and dedicated team to sift through flight schedules and keep track of announcements and service reductions and changes.
Wikipedia does a good job of that by its own nature and would be difficult for a site like airliners.net to compete with that.
I tend to use Flightmapper ( http://www.flightmapper.net). You click each end of the route and it gives you a list of airlines serving that route, you can then drill down to the full timetable.