Interesting! I ran across this interview* with travel expert Ben Schlappig today - even though not all of the tips suit our style, there are (at least) three cheap flight strategies that will probably work for us:
1) Start your trip somewhere else! Ben Schlappig calls it "positioning" - find a cheap city to fly from/to, then fly there. His example is round trip Cairo-NYC to save 90% off the reverse. Ours is Oakland-Stockholm to save more than 50%. Lucky for us, we stumbled onto this idea - but he has expanded it from a simple concept to a whole new level!
2) Patch together flights - get from one continent to another, then use local airlines to get to specific places within that continent. This is exactly what we're doing for our upcoming trip - and even with baggage and other fees, our flights add up to less than half of what our traditional method would have been.
3) I knew about airline hubs, but I had the strategy completely backwards! He says to yes, use a hub, BUT! When flying OUT of Airline X's hub, use Airline Z instead! "...the key is to fly an airline out of the city where they don't have much of a presence."
* read the interview here: http://www.vice.com/read/how-to-travel-the-world-first-class-when-youre-broke
see his blog here: http://onemileatatime.boardingarea.com