I think the Event Horizon was one of the scariest movie I have seen.
Not sure why, my wife thought it was nothing, but it freaked the heck out of me.
When I was a kid they used to have the "sunday horrors" on sunday evenings. I uesd to watch things like the Omen, Friday 13th, dawn of the dead, nightmare on elmstreet, Helloween, the exorsist..
More recently my fravorites are 20 days later and I am legend and the resident evil series (particularly #3).