The most amazing bit of dialogue in a movie has to be the scene between Christopher Walken and Dennis Hopper in True Romance. Both actors have so much presence, it's amazing to watch them interact throughout the scene. If you want to read the script check it out here:
http://www.pg.ru/scripts/true_romance.html
To find the scene search for "INT. TRAILER v DAY" and read on.
Jason Abels