1. THX-1138: There was a time when George Lucas really knew how to make movies. (Don't worry, he went back and screwed this one up with CG effects too.) This one came out before American Graffitti and was based on his student film project. To me it seems to be based on the Allegory of the Cave, but I have never heard anyone else make mention of that.
2. The African Queen: I have not seen this in years, but it made such an impression on me. Prior to this I appreciated old movies as art and had a respect for them as such. This movie entertained me as a movie. Not that there isn't art out the wazoo. You see Kate and Bogie demonstrate how good actors can be with little more than a small boat and each other to interact with. I was blown away! Some guy named John Huston directed it. I am not sure if he has ever done anything else.
3. Rushmore: How many other movies contain the secret to life? I don't think Wes intended this to be a laugh-out-loud comedy, but when we saw this in the theater my brother and I were dying. This is my kind of funny. And instead of going for the obvious 80's or indie avante garde soundtrack, the use of 60's British invasion tracks give the film a distinctive feel.
4. The Good, the Bad, and the Ugly: If you have no idea what makes a film great, this is still a kisk-ass movie. This is also probably the only trilogy with the best movie last. Sergio Lenoe's famous Man With No Name spaghetti westerns started with A Fistfull of Dollars and continued with For a Few Dollars More. Every angle and close-up used in subsequent showdowns seems to ape these movies. They will ofetn even evoke a thinly veiled homage to Ennio Morricone's haunting howl and whistle score for good measure.
5. 12 Monkeys: I heart Terry Gilliam. I could have just as easily put Brazil or Time Bandits on here. But I was in a 12 Monkeys kind of mood. If anyone can find or generate a screenshot of Bruce Willis sitting on the edge of the hotel bed in a ratty cardigan and a tee shirt with iron-on letters spelling "Chris," I would be endebted to them. (I intend to use this to creat an iron-on for a tee shirt to wear myself. )