Threads was DEFINITELY scary.
I also used to hate standing on the platform in Tube stations for some reason. It was something to do with the dark tunnels and the way the trains appeared almost without warning. And the rats on the line. You don't see many rats on the Tube now, or at least I...
I daresay the special effects are quite appalling now, but the scene in one of the Indiana Jones movies where the Nazi guys start melting was DEAD creepy.