random stream of conciousness brainstorming here:
1) looks like a spider. spider made of living wood. camouflaged spider (think predator movies). spider that only attacks impaired (drunken/wounded/mentally ill) prey. carnivorous tree with spider-esque "hunting limb". regular tree that grows scary shapes as passive defense.
2)cool picture. psychically "invisible" tribe (not really invisible, that's why they have shadows, but have auto-psychic effects so your mind refuses to see them, it's a first-white-man-seen situation and the researcher gave them shoes in trade/good-will gift), rain that makes things invisible when wet (they are wearing parkas that come down to their ankles, so shoes are dry but everything else is covered by wet/invisible parka)
3)photographer can't keep his hand steady. I don't see anything creepy about this pic.
i think the very first picture is your best bet. all i could think when i looked up in the corner was "everyone at that party is dead now, and all of their eyes are missing".