Considering that both flightaware and DUATS know and accept a fair bit of data about foreign airports, please consider allowing them to be named in the flight planner widget as origin/destination.
Which part(s) of the world are you interested in support for?
My particular itch is Canadian airports.
…and the Caribbean. 8)
thanks!
You may want to see a doctor for that. 
Would Mexico be possible? Not that I would plan a flight there anytime soon, but for vacationers that go to Cabo, Cozumel, Cancun, etc.