Go Lite is justly famous for living up to their name. I've found their 2lb Speed pack insanely useful despite - perhaps because of? - the fact that it appears to be manufactured from excess sheepskin condom material.
I've abused this pack through southeast Asia and northern Africa with no problems. The four mesh side pockets are great for trips where you want to have a lot of stuff immediately at hand without the need to open up the pack, or even take it off if you're with a friend.
Go Lite still managed to include along with generous 3,200ci capacity a tool loop, hydration sleeve, key pockets on the waist belt, stuff-it straps on the front and a removable top pouch. The lack of a frame limits loads to under 30lb, but under that limit the Go Lite Speed shines.