Body, UWA, Fisheye, Mid-range zoom, 80-200 are always in there for skiing or hiking.
remotes, stands and strobes and battery are in a separate backpack for urban or park shooting (depending on the day)
300mm, skins, shovel, probe, lens cloth and an extra pair of goggles are in there for the BC or powder shooting in general.
When I'm not shooting skiing, it really varies upon what I need.
Sometimes I'll bring a film body or my TLR for the fun of it as well. That's always a good time!