I watched Signs last night. Barring the dodgy effects in the last ten minutes, I spent most of it in a pretty much clenched state. In particular: the news footage of the children's party. And also a couple of the torchlight shots; they might well be an easy sort of scare but done right it's spectacular.
In any case, I think the best measure of these things is whether you get a twinge while walking down a dark corridor immediately afterwards, or when your turn off the lights and you're alone in the house. I don't mind admitting I had a little 'pull yourself together man' moment, before straightening up, setting my moustache flush and striding off purposefully.
Not had that feeling for a while. I think [REC] was the last thing to manage it. Before that I think it was the Bodysnatchers remake with Donald Sutherland, which is fucking horrendously uncomfortable from start to finish. Don't Look Now is great, but man; I could do without the sex scene.
What else am I missing? First person to say Event Horizon gets a disapproving look.