The Tell-tale Heart is a great story. I've heard people debate whether the murderer hears the old man's beating heart because he's made or if it's his guilty conscience. Surely the description he gives of himself watching the old man every night, finally creeping into his room, and being driven mad by the old man's eye speaks to his insanity... however, I think it's his guilty conscience over killing the old man which causes him to hear his heart.
I always enjoy The Black Cat. That he walls up the cat with his murdered wife and it gives him away is great... especially as he believes that it is the cat he killed. The Pit and the Pendulum is an interesting read, but for some reason I don't enjoy it as much as his other stories. I still enjoy it more than, say, The Great Balloon Hoax or Berenice, but it's not one of my favorite's of Poe's.
Jackie