Has anyone seen Rob Zombie's "Halloween"? Fucking awesome scary movie. Genuinely dark and terrifying. I think that is the best scary movie that has been made in the last few years.
Obviously, the best scary movies are the older ones that had an original plot and were truly scary. I.E. The Shining, Stephen King movies, etc...
In terms of lately, I'd say that "Sinister" and "Insidious" were decently scary. Especially that creepy ass dude in Sinister, he made the movie. Some other favorites are "The Devil's Rejects" (which is probably more on the 'fucked' side than the scary side), The Texas Chainsaw Massacre (2003 version), 28 Days Later, The Descent (that whole cave thing was really fucked), and The Sixth Sense.
What are some of your guys favorite scary movies?