Empire Magazine has used a combination of reader input, "Hollywood's finest", and film critics to produce a list of the 500 Greatest Movies of All Time
. A few key entries (in the top 100, haven't gotten through others yet) are Raiders of the Lost Ark at #2, The Empire Strikes Back at #3, Star Wars (A New Hope) at #22, LOTR: The Fellowship of the Ring at #24, LOTR: The Return of the King at #34, E.T. at #47, LOTR: The Two Towers at #54, and Return of the Jedi at #91.
There are other favorites from the forums on the list, but I didn't want to list them all here (other related movies are Temple of Doom at #233, The Last Crusade at #306, Revenge of the Sith at #330, The Phantom Menace at #449, and the Kingdom of the Crystal Skull at 453). Also, the Godfather was #1.