OK, now I see why John still doesn't understand my question at all. John is looking at this from the perspective of a person who already has a set list of cities he wants to visit, and just plugs them into a trip planner. Of course finding direct flights between *specified* cities is totally trivial, and not at all what I asked. Not sure where he got this since my original question clearly asks for all direct flights, not ones between a particular list of cities. John has it backwards.

I don't have an required order to visit cities in, I don't even have a mandatory list of cities. I am very flexible, just like the ticket I bought. Seeing the list of all direct flights will open my eyes to what is possible, and bias me in favor or against certain cities and routings. I might give a city with a direct flight, a second look. I hadn't considered the Seychelles until I spotted the direct flight from LHR for example. Likewise some cities cost twice as many segments to visit as others, and may move down the priority list.

If the list of direct flights is too long, it would still be useful to see all direct flights to/from a particular city. Note that is very different from asking about direct flights between two particular cities.

I have another list in mind that would be similarly useful to see. How about a list of cities that are served by more than one carrier or hub. Once you screen out hubs, this shows you places you can visit without any backtracking. For example you can fly from Barcelona to Athens on Iberia, and then Athens to Helsinki on Finnair. 3 carriers go to Moscow, etc...