Sleep deprivation seldom works for me and I am a bad plane-sleeper. (Not good - seems I'm always on the red-eye.)

I've found that I'm most able to sleep my way through a flight when I bring non-stimulating forms of entertainment. I'll get three rows into a knitting project or ten minutes into a lecture on my iPod before I pass out. If I try to read or watch a movie, I'm up for the whole flight.

Lectures and audiobooks on academic topics are particularly "useful" in this regard. (I love both, but the drone of the plane engine and the dark cabin combine with the lectures in such a way that I fall asleep, even when I don't intend to.)