I've had an obsession with F.E.A.R. 2 lately. Only one part got me to be honest though. In the first level (or second I forgot). You go into some room with an indoor pool, and if you turn around, there's Alma standing there and she vanishes after a split-second. The rest isn't that scary (I'm at level 10/16 so far though).

Lemme try to find a vid of the part.

Okay, it's at about 1:35