Just take a sleeping bag and slap some lines to it so it can be suspended like a hammock. Whether you camping in the winter and you want to sleep up off the ground, or you're a hammock lover who happens to live in Alaska, the uses are unlimited.
That sounds vaguely familiar - I think I've seen one of these somewhere. Yeah, see links. Won't be much help in Alaska, though.
There are tents that are made to be suspended from trees.