Well, my amazing wife got me a killer gift for Father's Day, a RAB Quantum Endurance 400, 25 degree mummy bag, stuffed with 850+ European Goosedown. It's under 2lbs, and it packs down to almost NOTHING. I can't wait for my first winter hang now!
The materials are pretty sweet. Pertex inner lining, and Pertex Endurance outer shell. Super light and highly water resistant. Man, I think this stuff would make a GREAT tarp if you could find it for a decent price, in quantity.