Two by Scorcese pop into mind:
Joe Pesci's 'Do I amuse you?/Funny how?' scene in 'Goodfellas' and DeNiro's 'You talking to me' monologue.

I always liked this one from American History X.

Bob Sweeney: There was a moment... when I used to blame everything and everyone... for all the pain and suffering and vile things that happened to me, that I saw happen to my people. Used to blame everybody. Blamed white people, blamed society, blamed God. I didn't get no answers 'cause I was asking the wrong questions. You have to ask the right questions.
Derek Vinyard: Like what?
Bob Sweeney: Has anything you've done made your life better?

Taxi Driver, surely. [Don';t call me surely.] But anyways...

"You talkin' to me? etc"

In fact you coule have a whole De Niro special section.

'Did you fuck my wife?' [Raging Bull]

Or was it The Flintstones?

http://www.youtube.com/watch?v=x_4lXncUTk4&feature=related

Hedley LaMarr (Harvey Korman) in Blazing Saddles "evil" monologue...

"A sheriff! Law and order is the last thing I want! Wait a minute... maybe I could turn this thing to my advantage. If I could find a sheriff who so offends the citizens of Rock Ridge that his very appearance would drive them out of town. But where would I find such a man? (to us, the audience) Why am I asking you?"

http://www.youtube.com/watch?v=p2o4ifVlMG4

No Country For Old Men:
"What's the most you've ever lost in a coin toss?"

Three of the most terrifying words ever uttered in cinema: "Is it safe?" (Lawrence Olivier in Marathon Man)

Joker: "Why so serious??"
The Dark Knight

Frances McDormand in FARGO:

“And for what? For a little bit of money… There's more to life than a little money, you know… Don't you know that? ... And here ya are, and it's a beautiful day… Well… I just don't unnerstand it.”


John Cleese in LIFE OF BRIAN:

“All right, but apart from the sanitation, medicine, education, wine, public order, irrigation, roads, the fresh water system and public health, what have the Romans ever done for us?”


Michael Madsen in RESERVOIR DOGS:

“Are you gonna bark all day, little doggy, or are you gonna bite?”


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I had desperately wanted to suggest the following lines from the brilliant opening scene to HAPPINESS, spoken by Jon Lovitz (who doesn’t appear in any later scenes):

“You think I don't appreciate art? You think I don't understand fashion? You think I'm not hip? You think I'm pathetic? A nerd? A lard-ass fatso? You think I'm shit? Well, you're wrong. 'Cause I'm champagne, and you're shit. And till the day you die, you, not me, will always be shit.”

The scene:
http://www.youtube.com/watch?v=EDEjQp6q_pQ

However, when I looked it up in the script, I discovered that all of those ‘questions’ were originally written as blank statements (I added the question marks to the version above).

I just can’t imagine the original intonation providing anything near the same kind of climax to what is one of my Favourite Opening Scenes of All Time.

Fodder, perhaps, for a separate post about the importance of writer/directors not becoming too attached to their prescribed ‘internal’ line-readings – and to treat actors as collaborators, not as sock-puppets?

DP

Hey, fantastic suggestions everyone! It's funny, but some of the most provocative and memorable lines are questions - that had never occurred to me. Perhaps there's a lesson to be learned, about the power of a question, how it can be both confrontational, and yet open-ended, and even that mood can have a wide emotional range.

Interesting...