1) Do stuff from this vid. And if you are sitting next to a (preferably hot) girl, do 0:41
http://www.youtube.com//watch?v=CJ8uymvLwt
BTW: Joel Heyman is hiding in that plane...
2) If you are good at accents, use one and make up a phony story to tell to the guy next to you in your accent. Then at the end of the flight get up and speak normally to say goodbye. (And make where you are from in your story the same place the accent is from, derp)
3) One of my personal favorites, and something I have been addicted to for as long as I can remember (and then some)...SLEEP.