I've also been meaning to mention that I finally saw Pitch Black, which I think Karen and various others had recommended. I'm not normally into horror movies (Scream is the only one I can recall particularly enjoying), and I'm very skeptical of the horror/SF genre. (I'll have to see Alien again before judging it; I saw it on a small TV in broad daylight with several friends who'd seen it before and were busy chatting about other things, and it didn't make much impression on me.) But this was a pretty fine movie. Good SF, good characters, only about two truly stupid decisions on the characters' parts (one of which could've been resolved with about one more line of dialogue regarding the orrery). Lots of surprises. Very tense. Good acting, especially by Vin Diesel (the voice of the giant in The Iron Giant, but better known for his role in Saving Private Ryan, and I seem to recall liking him a lot there as well.) Not much of the things-jump-out-at-you school of shock filmmaking. And the structure is really interesting—I don't think it's giving too much away to say that the first half turns out to be (fairly subtly) devoted to setting things up for the second half, like setting up dominoes in preparation to knocking them over.
I made the mistake of watching this in my apartment, alone, starting around 8:30 p.m., which meant it was well after 10 when I finished. I recommend seeing it earlier in the day. And if you really dislike scary stuff, you probably don't want to see this at all. But if you can deal with being scared as long as there's a good plot and characters, this is worth seeing.