Allen Carbert: There really is no formula for the perfect inventory of a backpack. What I do is observe a practical balance between my desire to travel light with greater ease, and the necessity of preparedness. If you want to go light and be prepared at the same time, items you carry must have multiple uses or be useful in variety of conditions. These are some things that seem to find their way into my pack time and time again.
I usually carry 2 heavy weight trash compactor bags. Super-light and versatile. I use these for keeping the contents of my pack dry if it’s raining or snowing. They work better than silly backpackers pack covers that are not meant for mountain climbing in the first place. Another use for compactor bags is to load them up with clean snow for melting. Keep it near the stove and have a convenient source of clean snow for water. I have used them under my sleeping bag as a moisture barrier between my sleeping bag and dirt or a wet tent floor. I’ll use them to compartmentalize super wet or dirty gear during and after a climb.
Another thing is this old nylon windbreaker anorak jacket. I think I bought it in 1997 and paid $12 for it. I have brought this jacket to many mountain tops. It is super light, packs up the size of a tennis ball. As a windbreaker it does well for what it’s made for, breaking wind, ha! On breezy days I wear when the chance of rain is minimal. Perfect for settled weather when the temps are moderate and a light breeze is present.
Over a stack of pile jackets I have taken this one to the top of Kilimanjaro well over a dozen times. For high activity days in clear cold weather it is super -breathable and fits well over pile jackets. I also wear this jacket when the mist or drizzle isn’t enough to warrant full Gore-tex rain gear but I want something over the poly pro to keep drier. Another climate I use this jacket in is for sun protection on glaciers when the heat is on. Used over a light layer of poly pro it keeps you cool and protected from the sun.
Jon Holz: The Patagonia Puffball Pullover. "That style sweater is one of the best developments--light, warm, wind resistent. Damn I sound like an advertisement. It always goes in an overnight pack and generally makes it in my day pack, too."