While it was designed specifically for hunters to hang weapons from, Montie Design's Tree Hook would make an excellent camping aid as well. The 7-ounce device consists of a strap, buckle and aluminum protrusion that braces itself against a tree trunk and protrudes like a shelf bracket, letting you hang cooking gear, bags, towels et cetera.
Their Camp Rack is similarly tree-mounted, but this one featuring rows of protrusions so you can hang multiple objects.
Montie Design is based in Morrisville, North Carolina, about five hours east of a rugged area in the mountains called Troublesome Gap. One of the cool things about the firm is that they take their staffers and products out to Troublesome Gap to do real-world testing, and document it on their website.