I can't help myself... I must post my favorite ROTK quote. (It's not from the extended edition.)
Sam: What're you doing? Sneaking around, are you?
Gollum: Sneaking? Sneaking? Hobbitses always so polite. Smeagol leads them to secret places that no one else can find, and they say "sneak!" Oh, very nice, precious, very nice.
Sam: Alright already! You just startled me is all. What were you doing?
My second favorite would have to be:
Gimli: Certainty of death. Small chance of success. What are we waiting for?