Steam Boy - This is my favorite sci fi movie of all time. It's pure brilliance. The detail is impressive, from the Manchester dialect to the very long train scene (you'd know it when you see it)
Steamboy - Official Site Saturn 5 - This is a great suspense movie. I loved it.
Demon Seed - The AI was very believable.
AI - I loved this movie. It fascinated me to see these main characters figuring out how to deal with their various problems... you could almost see the gears churning.
I, Robot - Great action scenes and a decent story.
Star Trek - The Motion Picture - Everyone seems to hate this movie but me :(
Clash of the Titans - I have no idea why I like this movie.
The Day the Earth Stood Still - I love the moral. It was an intense movie. I'd like to see a remake.
Alien and Aliens (Alien II) - These are almost ideal sci fi movies: gritty, raw, real, and some horror and suspense thrown in.
The Matrix (just the first one) - This was incredibly original and had me from the first scene.
Equilibrium - I love how a puppy changed this brutal man's character.
Blade Runner - I saw it as a kid and it creeped me out, but it deserves it's cult status.
Stargate - An underrated movie. I love these "ancient futuristic" movies.
Chronicles of Riddick - This movie showed all the workings of a technologically-advanced but culturally-primitive society that was fascinating. Everything was so big.
Terminator (just the first one) - This is one of the best sci fi movies ever made. It was somewhat like Saturn 5 though, so I feel it lacks in originality.
The Mist - I loved this movie... including the ending!
Sky Captain and the World of Tomorrow - I know many people who hated this movie, but i have to say that I loved the 50's sci fi theater feel.
Silent Running - Loved Huey, Dewey and Louie! Awesome ending that I can't mention here
Sunshine - The ending sucked, but this is how I like my sci fi -- gritty and raw.
The Animatrix - The second story explained the origins of the matrix from the very beginnings.
The Andromeda Strain - This was a very intense movie.
Minority Report - I didn't like it as much as Ebert (it was his favorite movie of the year) but I enjoyed it
The Abyss - The CGI is still impressive. I loved the mini-sub demolition derby.
Serenity - Much better than the series
Contact - So much better than Sagan's book
Soldier - A very simple plot. Reminiscent of Shane
Predator - Mostly a hunt that didn't really need the sci fi element, but that made it more interesting.
Twelve Monkeys - Barely sci fi, but an awesome complex story that is very engaging.