I'm coming, I'm coming. As for "trashy" films, Texas Chainsaw Massacre seems like a fairly obvious choice. Other good horror films that were hugely influential both to future directors and pop culture could be Night of the Living Dead or Halloween. Halloween pretty much started the slasher craze, and Night of the Living Dead is low budget Indie film making at its finest. I'm also partial to Black Christmas as it pretty much invented every modern horror cliche (faceless killer, first-person camera perspective, abrasive "protagonists" and probably a few others I am forgetting). I think it is kind of odd that Metropolis or M aren't mentioned. M pretty much was the beginning of film noir and really showcased how directors could use sound in a film by have a distinct lack of sound. Pretty much every crime film and thriller pays something to M. And Metropolis is a hugely influential sci-fi film as well as a being filled with numerous technological achievements. Tim Burton, Terry Gilliam and Jeunet/Caro practically owe their careers to Metropolis, and it is clearly influencing films like the Alien franchise, Brazil and Bladerunner. Then of course you have movies like The Rules of the Game, Ten Little Indians and Seven Samurai which are influential for their iconic stories which have been remade, reworked, redone and ripped off countless times. And it might be considered cheating but I really think A Trip to the Moon should be on the list no matter what.