This method is popular with ultralight thru-hikers and requires two materials that you don't normally carry (cord and carabiner). Like all bag hangs, it can be foiled by smart, food-conditioned bruins. Check regulations to make sure bag hangs are legal.
The best knot out there for tightening and releasing cords that will be heavily loaded. It's perfect for cinching down gear, tensioning horizontal spans of rope, or getting a large tarp tightly pitched.