..but I'll settle for "okay" Sci-Fi at this point. I've got to the point where it feels like I've seen all the good Science Fiction, but surely there's something else out there. Maybe something foreign or obscure that I've missed, or maybe something obvious that I'm just forgetting. Let me try to make a list of all the Sci-Fi movies that I've seen, and then you guys just start throwing out as many suggestions as you can think of. Preferrably outer space Sci-Fi and preferrably from the past 30-40 years or so, but it doesn't nessecarily have to be.

12 Monkeys
2001
2010
A.I.
Alien 1 - 4
Alien vs. Predator
The Abyss
Adventures of Buckaroo Banzai
Arival 1 & 2
Atlantis
Back to the Future
Barbarella
Blade Runner
Brazil
Chronicles of Riddick
Close Encounters of the Third Kind
The Day the Earth Stood Still
Dark City
Dune (1984)
Dune (2000)
Children of Dune
E.T.
Equilibrium
Evolution
The Fifth Element
Final Fantasy
Galaxy Quest
Hitchhiker's Guide to the Galaxy (1981)
Hitchhiker's Guide to the Galaxy (2005)
I, Robot
Ice Pirates
Impostor
Independence Day
Jurassic Park 1 - 3
Killer Klowns from Outer Space
Lifeforce
Logan's Run
The Matrix
The Matrix Reloaded
The Matrix Revolutions
Men in Black 1 & 2
Metropolis
Minority Report
Natural City
Pitch Black
Planet of the Apes
Predator 1 & 2
Quiet Earth
Signs
Sky Captain and the World of Tomorrow
Solaris (1972)
Solaris (2002)
Spaceballs
Spacehunter: Adventures in the Forbidden Zone
Star Trek I - X
Star Wars I - VI
Stargate
The Stand
THX-1138
Terminator 1 - 3
Total Recall
Treasure Planet
Tron
War of the Worlds (2005) (I'll have seen it by tomorrow anyway )
Wonderful Days

I know I'm missing some stuff from this list, so just throw out as many movies as you can think of. The fate of my weekend may rest in your hands.

Check out the Battlestar Galactica miniseries if you haven't seen it already. It's excellent.

City of Lost children is a really good (and kooky) sci fi film by Jean Jeunet. It was made in collaboration with Mac Carro and thus is darker than any of Jeunet's recent stuff like Amelie and A Very Long Engagement. It's very imaginative though.

You seem to miss some great Carpenter sci fi's such as They Live!, The Thing, Escape from New York, and Big Trouble in Liittle China. You're also missing some key Cronenberg sci fi films such as The Fly, The Fly 2, The Dead Zone, Scanners, Videodrome, and eXistenZ.

You could try
13th Floor
Event Horizon
Mad Max 1-3
Gattaca
RoboCop
Time Bandits

I bet you saw all these and just forgot to list them

Primer

Explorers
Strange Days
Starship Troopers
1984

Cube
Pi
Avalon (2001)
Ghost in Shell 1 & 2
Battle Royale
Nausicaa
Bill and Ted's Excellent Adventure / Bogus Journey
The One
Eternal Sunshine of the Spotless Mind
Open Your Eyes / Vanilla Sky
Returner
Juvenile


Little known, and hard to find, but also very interesting:
Nabi

A few more:

Transfomers
Lilo and Stitch
Paycheck
Young Frankenstein
Animatrix
Small Soldiers
Batteries Not Included
Cocoon
Mom and Dad Save the World
The Truman Show

Planet of the Apes series
Soylent Green
Omega Man
Invasion of the Body Snatchers
Iron Giant
Titan AE
Steamboy
Cowboy Bebop (movie, also a series)
Flash Gordon (more for camp and soundtrack than good scifi)
Explorers

What, no Dark Star?

2009 Lost Memories (Korean)
Andromeda Strain
Enemy Mine
Last Starfighter
Outland
Red Planet
Roughnecks: Starship Troopers Chronicles
Soldier
Them

Harryhausen movies

Babylon 5 - ok not movie but very good sci-fi

Actually I've never seen it. But that does remind me of Star Man, which is another to add to the list.

Akira
Forbidden Planet
Earth v.s The Flying Saucers
Them
The Andromeda Strain
The Thing From Another World (1951)

If you'll settle for a television series, I thought Firefly was pretty good.

Contact
Altered States
K-Pax
Twilight Zone The Movie

Watch Cowboy Bebop, DAMNIT. There's a good 13hrs there for you.

Both the 1956 and 1978 versions of Invasion of the Body Snatchers are highly recommended.

(As a subtext in both - in the 1956 version, the Body Snatchers can be interpreted as Red Scare Commies; while in the 1978 version, the Body Snatchers can be interpreted as Republicans! )

I love Cowboy Bebop.

I also love Serial Experiments Lain, IMHO, best scifi in the last decade - despite it being animated. (13 episode series)

Also:
Kin-Dza-Dza
A Clockwork Orange
Donnie Darko

Storm of the Century
Mission to Mars
Apollo 13 (somewhat fiction)
Armageddon
Fantastic Voyage
Gremlins
Sphere
V (which I hear they're remaking)

Stalker

Someone already said Enemy Mine, but that's a great movie.

Also others I didn't see mentioned:
The 6th Day
Butterfly Effect (kind of)
Frequency
Hollow Man
Krull
Masters of the Universe (kind of)
Multiplicity (more of a comedy actually)
The Running Man
Short Circuit 1 and 2

Silent Running
Excalibur
Invaders From Mars (1953)
A Boy and His Dog
The Time Machine (1960)
Screamers
Near Dark
Time After Time
The Hunger

Also, some great TV sci-fi, not hard science fiction but with sci-fi elements, can be found in Buffy, the Vampire Slayer, Angel and The Prisoner.

Night of the Comet

Leviathan

started typing out a bunch and then looked up and most of them have been suggested already - so nevermind.

Fahrenheit 451
Seconds
Quatermass and the Pit
Contact

No one mentioned Quantum Leap TV series?

Movies:
American Astronaut
Cube
Cypher - DVD Release 8/2
Day the Earth Stood Still
eXistenZ
Gattaca
Immortal (Stargate Like)
Open Your Eyes
Paranoia 1.0
Pi
Primer
Thirteenth Floor
X-Files - Fight the Future

TV Series:
Battlestar Galactica 04
Battlestar Galactica 03 (TV Miniseries)
Earth 2 - DVD Release 7/19
Farscape
Farscape Peacekeeper Wars (TV Movie)
Firefly
Red Dwarf
Sliders
Stargate SG-1
Tomorrow People
X-Files