Dune !

• District 9
• 2001: A Space Odyssey
• Star Wars: The Empire Strikes Back
• TRON
• Plan 9 From Outer Space

And AVATAR, which I just loooooove to hate.

Blade Runner

Dark City

Planet of the Apes (original)

Appleseed

Pitch Black

The Chronicles of Riddick

Ghost in the Shell

The Matrix

Screamers

The Arrival

Contact

Mimic

Event Horizon

Alien

Terminator

Predator

The Cave

K-Pax

Starman

District 9

The Road Warrior

They Live

Gattaca

Prey Alone (Atom films short)

2001 gets honorable mention as does Solaris and The Time Machine (2000), Serenity...and if you could combine the best strengths of The Red Planet and Mission to Mars into a single film it would have been pretty awesome.

...and Invader Zim should sooo have been a movie.

Hmm. This is a bit of a hard one.

In no particular order:

I, Robot
Pitch Black
Alien
Aliens
The Hitchhiker's Guide to the Galaxy
Titan A.E.
The Ultramarines Movie 

Also, all six Star Wars movies. Because they're all pretty epic.

I'll probably pick up flak for liking the Ultramarines Movie, as it was generally regarded as not very good. But it's also the only 40K movie around, so I like it anyway.

This. Because I hate that movie on principle. I mean really, a bunch of spear-toting natives beat down an interstellar-capable civilization? Do they not realize just how stupid that is?

Because any real interstellar civilization wouldn't have bothered with the natives. They'd just wipe 'em out, and then claim all the "unobtainium" (really, Cameron? Really? That's the best you could come up with?) for themselves.

Also, because I hate blue monkey people that are supposedly more moral than humans. Said blue monkey people don't have the slightest concept of what mankind has faced, and overcome. They are in no position to judge.

I actually spent some time figuring out how the Human faction could have conceivably lost. They just need to have really substandard equipment and around 100-to-1 odds.

My issues weren't so much with the many scientific, technological, and tactical slipups (although they most certainly did not help) so much as with the Gaiistic technology-is-evil nonsense. Ok, so it's probably not morally advisable to use big men with big guns and little accountability to force them off of their land, since they were technically there first and therefore own it by default. But that doesn't mean that the entire Human culture is responsible. The idea of Jake and the resistance Humans just throwing away all of the technological marvels they've achieved and going off to live in the jungle, hunt for food every day just to survive and finally die at around 30 is so messed up I can't even begin to put it into coherent words. Does he even realize that the only reason why he's there AT ALL is because he flew there on a STARSHIP and is walking around in a genetically engineered surrogate body?

The anti-technology sentiment in Avatar was probably over emphasized.

I still don't understand why some Star Wars fans either hate the Prequels and refuse to call the original film A New Hope or hate the Original Trilogy, it is meant to be treated as one epic saga, not individual films.

Good discussions here

Any more people willing to share their favorites?

I think it has to do with the fact that the Original Trilogy was a very fun series of movies; they were a bit serious but at the same time they were funny and, moroever, just plain fun to watch. The Prequels started to move away from this a little bit, particularly with Episode III, which was pretty dark, especially compared to the rollicking fun of the OT.

Rather ironic, though, isn't it, that even though in ANH a planet gets blown up and billions die from it, but it's not a dark and depressing film.

I know we are talking fav's, but a decent one that just came out:  source code.  Watched it today and it was a good time.  If you are a sci-fi fan, I think you'll enjoy.  Not the world's greatest movie, but it was fun.

Source code seems fun. I will give it a try once it is in theatre here.

Should one see the tv series first before watching Serenity?

My number 1 pick is easy: Bladerunner

The remaining choices are more difficult so I'll list a few in no particular order:

2001 a Space Oddyssey, Gattaca, Sleeper, Forbidden Planet, Aliens, Brazil, Dark City, A Clockwork Orange

Well, crap. I saw the movie before I even knew that the series had actually existed.