If you're interested in film, you must have heard of Orson Welles' Citizen Kane. Often refered to as the greatest movie made. Maybe not the best ever, but it is pretty good IMO. The trailer is cool. It's not like your average trailer: It starts with Orson Welles adressing the audience (with a voice-over, we never see him in it), talking about the film. He introduces the actors, when he's finished with that, we get to see charaters talking about Charles Foster Kane, some love him, others doesn't. Then Welles adresses the audience again, and tells us to go see the movie and make up our own mind about Kane.
Check it out here, 13,5Mb.