There was a time when I resorted to collecting in-flight magazines of every airline I used just so I can check out their route maps and plan my future trips accordingly. It’s hard to believe but even during the internet age, many airlines initially did not post their route maps on their websites; leaving prospective passengers guessing how to get from Point A to Point B.
Later on, I discovered that Wikipedia had a fairly reliable list of destinations for almost all operating passenger aircraft carriers. While the information was exhaustive, it lacked one crucial element. It still did not state Point A to Point B destinations, the best it could do was provide a list of all destinations served by various carriers.
Then came Openflights, which provides a wealth of information for people who have trips in mind. I can simply type any airport code in the search field (i.e. SIN) and it generates all the direct routes from that airport on the map, complete with distance and flight duration. Alternatively, I can input any airline and it will show all the routes being served. As of now, it does not show flight schedules – but even then, Openflights is a very handy tool for those who want to plan their trips efficiently.