I’m a side/back/stomach sleeper (yeah…I move a lot) — and I CAN’T sleep without a good, firm pillow.
I just discovered a very light inflatable pillow that I think might be the answer I’m looking for at http://www.flexair.com/
They’re reusable (although not indefinately), cheap (< $0.50 each in quantity), and very light (< .75 oz). They're SO light that I could easily carry a spare in case one pops on a trip and still save 5-6 ounces. Has anyone tried these before? They look like they might be the same as the core used in the Luxury Lite pillows.

