YES! I saw "Paranormal Activity," alone, at a theatre. That movie did not scare me one bit.
However, another movie I saw, alone, in a theatre (I think I may have been the only one because it was a matinee) was "The Strangers." That movie REALLY gave me the creeps. Very frightening moments.
What bothered me most about this movie is that it was based on TRUE EVENTS, something that really happened.
I am an avid movie lover. I have seen many films that I can hardly remember what happened. However, I have never forgotten "The Strangers." Scared the life out of me!