I'm also a big fan of the Wendigo. love the myths involved, and they're a great background evil that eventually jumps out and gets you to eat the rest of the party, before you go off to do that to someone else.
they're disturbing, scary, and a clash between taboo and primal needs. Makes them a great monster in my book.
also the Atropal, something about dead god foetuses (wow that's a weird looking word) just make a good dark and stormy night story.