AviNation is an airport-management social game slated to hit Facebook in June.
I bailed from Facebook about two years ago and don't miss it at all. It is the biggest, most insidious time-waster on the Internet. Every now and again I get an urge to go back, but fortunately it quickly passes.
Also, Facebook creator Mark Zuckerberg is so much like Bill Gates that it's uncanny: silver spoon rich kid, Harvard dropout, stabbed many people in the back on his way to the top. But I digress.
On a more pleasant note, I would like to see a combat aviation MMO where the player creates an avatar/character that can do things between missions like shop for aircraft upgrades and equipment, join a squadron, hang out at the base cantina and chat with other players, etc. I think it would be kind of boring to have an aviation MMO where you're sitting in your plane the whole time. On a related note, I think Star Trek Online had the right idea by doing something similar to what I described. The trouble with STO, however, is that the missions are repetitive and grindy after a while, there's way too much instancing, the PvP are meaningless one-off matches, and there's not much motivation to play after you reach your level cap.