I have found this top website on my trawls, I thought I would share with you all.
http://screentalk.biz/moviescripts/ will show you the scripts and screenplays of all the movies on the list.
My personal favourite is the script to Aliens possibly the film that has scared the sh!t out of me more than any other film has in my life. I'm on Page 50 at the moment, just getting good, those facehuggers are scary sons of bitches though.