We tend to have a lot of winter in my area. Hence I tend to do a lot of winter stuff.

In winter, I always have a rolled up closed cell foam pad secured on my pack. Mine is about 3/4 length. If I get stuck out overnight (even above timberline) I can use my avy shovel to improvise a shelter (snow cave, tree well, ranger trench, whatever). I can then use the pad plus my pack to lie down on. I consider the pad to be an essential peice of winter gear.

Closed cell foam pads are also an excellent first aid item. They can be used to make several different kinds of dandy improvised splints. The can simultaneously immobolize, cushion, and insulate an injured limb. If everyone in a team carries one, you can put one under an injured person, and use others to splint him/her.