I noticed a lack of Anime. If I may:

Ghost in the Shell (the entire collection if you have the time)
Macross: Do You Remember Love?
Akira
Galaxy Express 999
Captain Harlock
Battle Angel Alita
Serial Experiments Lain (Series)
BubbleGum Crisis Tokyo 2040 (Series)
Red Baron (Series)
Saber Marionette (Any, but J is a series that hits maturity in the second half with aplomb)
Neon Genesis Evangelion (Series)
Cowboy Bebop (Series)
The Big O (Series)
Roujin Z
Final Fantasy VII: Advent Children
Iria: Zeiram the Animation
Steamboy
Paprika

And more I can’t think of right now.

Also, if you count ~20 year old movies as classic, I’d add Bicentennial man and Artificial intelligence, haven’t seen these mentioned yet.

Ooh, I have a list:

• Looker - directed by Michael “Jurassic Park” Chricton. The first ever film to create 3D shading with a computer that produced the first ever CGI human character was the model Cindy (Susan Dey).
• Westworld (1973) - also written by Michael Chricton
• Mac and Me - It’s a movie that’s SO UNBELIEVEABLY BAD IT MUST BE SEEN TO UNDERSTAND HOW BAD IT IS. After you watch it, you’ll understand why Paul Rudd tortured Conan O’Brien with this famous clip.
• The Last Starfighter - another cheeseball 80s knock off of Star Wars. Also pioneered the use of CGI
• Enemy Mine - Dennis Quaid bonds with an alien enemy and eventually helps him bear children. Directed by Wolfgang ‘Neverending Story’ Petersen. You have been warned.
• The Quiet Earth - A scientist awakens to find himself alone in the world. In a desperate attempt to search for others, he finds only two who have their own agenda.
• The Stuff - A delicious, mysterious goo that oozes from the earth is marketed as the newest dessert sensation, but the tasty treat rots more than teeth when zombie-like snackers who only want to consume more of the strange substance at any cost begin infesting the world. Co-stars Paul “Goodfellas” Sorvino
• Miracle Mile - What would you do if you accidentally found out that the world was ending in a little over an hour? Features Anthony “ER” Edwards

I guess most of the famous classics are going to be listed anyway, so to add something that most people probably haven’t seen, I suggest *batteries not included. It’s nothing grandiose (more like a family-friendly flick, I feel like it’s in the same category as Flubber or Short Circuit), but it’s really sweet, light-hearted and enjoyable.

Lol at Zardoz being on anyone’s “must see” list.

Some that I’m not seeing here much yet:
Hitchhiker’s Guide To The Galaxy, War of the Worlds, Minority Report, Gattaca, Heavy Metal, Repo Man, Starship Troopers, The Fifth Element, Tron, Tron Legacy, Independence Day, Idiocracy, Predator, Star Trek (2009), Escape From New York, Galaxy Quest, Total Recall, Close Encounters Of The Third Kind, E.T., Wall-E, Jurassic Park (1993), District 9, Robocop, Children of Men, Inception, and the Back To The Future trilogy,

If you can handle subtitles Tarkovsky’s 1972 version of Solaris is brilliant.

Forbidden Planet, Logan’s Run, Death Race 2000, The Day the Earth Stood Still, …

What’s your cutoff for “classic”? Are we talking about the classic film era, or anything older than 25 years?