1.) The original Star Wars trilogy
2.) Raiders of the Lost Ark, the sequels less so.
3.) Clash of the Titans - the remake comes out this spring. It looks just like 300. Sigh.
5.) Airplane! and Airplane II
6.) Every Which Way But Loose
7.) The Cannonball Run and The Cannonball Run II (though not as much as the first one).
8.) The first three Muppet movies - The Muppet Movie, The Great Muppet Caper, The Muppets Take Manhattan
9.) Poltergeist - don't ask me why, it still scares the living shit out of me.
10.) Back To The Future
11.) Close Encounters of the Third Kind
Honorable Mention: Dune
I didn't get around to reading the books until I was a teenager, but those giant worms always fascinated me.
Notably Missing: E.T. - never understood what the big deal was.