Speaking of No Country for Old Men, I think the scene where Sheriff Ed Tom Bell and deputy go out to look at the massacred drug dealers is one of the best in film. These lines are so great:

Sheriff Ed Tom: “It sounded like these old boys died of natural causes.”
Deputy Wendell: “How’s that, Sheriff?”
Sheriff Ed Tom: “Natural to the line of work they was in.”

I can’t remember if those lines are in the book — been too long since I read it — but damn that is some dialogue writing there.