Complete step-by-step instructions on building a home-made alcohol ultralight stove from a soda can. These work well on the trail. Boils a pint of water in just over 4 minutes on just a half-ounce of alcohol.
If you need to pitch a tarp or tighten a fly, you can make an impromptu tarp clip from a split twig, a matchstick and a bit of string. Works best if the clamping part is long enough to go over the folded edge of the tarp.