Donnie Darko... don't watch that if you're feeling mentally exhausted -- it's a good movie, but you'll need your thinking hat on. Not something to watch if you just want some mindless entertainment (I guess that's more like what Michael Bay excels in :p).
There's also "Devil" by M. Night Shyamalan (checks Google - yes, I spelt it right! :D) - the same director as the Sixth Sense. Apparently that's going to be the first in a series (trilogy?) he's working on.