John Scalzi's The Rough Guide to Sci-Fi Movies just came out and one of the chapters is "The Canon: 50 science fiction films to see before you die". There has been, of course, plenty of debate about John's choices, but it's also a great chance for a meme! Ones I've seen in bold:

• The Adventures of Buckaroo Banzai Across the 8th Dimension!
• Akira
• Alien
• Aliens
• Alphaville
• Back to the Future
• Blade Runner
• Brazil
• Bride of Frankenstein
• Brother From Another Planet
• A Clockwork Orange
• Close Encounters of the Third Kind
• Contact
• The Damned
• Destination Moon
• The Day The Earth Stood Still
• Delicatessen
• Escape From New York
• ET: The Extraterrestrial
• Flash Gordon: Space Soldiers (serial)
• The Fly (1985 version)
• Forbidden Planet
• Ghost in the Shell
• Gojira/Godzilla
• The Incredibles
• Invasion of the Body Snatchers (1956 version)
• Jurassic Park
• Mad Max 2/The Road Warrior
• The Matrix
• Metropolis
• On the Beach
• Planet of the Apes (1968 version)
• Robocop
• Sleeper
• Solaris (1972 version)
• Star Trek II: The Wrath of Khan
• Star Wars Episode IV: A New Hope
• Star Wars Episode V: The Empire Strikes Back
• The Stepford Wives
• Superman
• Terminator 2: Judgement Day
• The Thing From Another World
• Things to Come
• Tron
• 12 Monkeys
• 28 Days Later
• 20,000 Leagues Under the Sea
• 2001: A Space Odyssey
• La Voyage Dans la Lune
• War of the Worlds (1953 version)

34 out of 50, if you're keeping score at home. Not that it's a contest. Unless I'm winning.