Signs/Nightmare Fuel

• The scenes that keep the aliens offscreen except for brief glimpses - such as in the cornfield, home video footage, and hell, even trapped in that guy's room - are both startling and quite unsettling, as are the character's reactions.
• The pantry scene. Oh, gosh, the pantry scene.
• Another example of brief glimpses being scary as hell: a certain scene has an alien arm sneaking behind the kid -- just before the lights go off. It made my aunt scream (and wonder why her husband was laughing).
• The disturbing video of the birthday party. Just the sudden music staccato and the humanoid alien appearing so suddenly... .
• The family has just finished getting the house secured when they suddenly realize that they forgot to bring their dog inside. Right at that moment, they hear the dog start barking hysterically, and a moment later she whines in agony and then all is silent until footsteps are suddenly heard on the house.
• Just about any scene at all from the moment the aliens enter the house. Why? Because you can hear their clicking, see their shadows, hear their footsteps creak on the rafters, but you never see them. And after watching the rest of the movie, it's almost impossible not to be gripping the arms of your chair, just waiting for something to jump out at any second.