From Fastco Design, James Lee designs a better armrest for airplanes:
[The] concept for the Paperclip Armrest has a double-decker configuration, effectively putting two arm rests in the space of one. No more sharing. Your neighbor’s arm goes on the bottom level while yours fits on the top. (Battle over that, if you must.) There’s a roughly three-inch gap between the two layers, so it’s still cozy, but not horrifically so.
Great design for a problem that I always seem to have. Click through for pictures. Of course, we can’t even get airlines to board flights efficiently so good luck getting these installed.