The title sets the topic for the thread. Give your reasons; posts like “Asprin’s Little Myth Marker” as the total text of the post are the ultimate in boring reading. Comments on who ought to make the movie, who you’d cast as the major roles, etc., would be interesting, as well.
I’ll reserve my answer until I’ve seen a few others.
Hmm. It’s been a while since I’ve read it, but I think Niven’s The Mote in God’s Eye would make a good film. Unlike some books I can think of, the science-fictiony parts of it wouldn’t require any ground-breaking special effects (don’t think it would take anymore then an episode of DS9 did), so they could be done well enough so as to not distract from that whole “plot” thing that seems oddly absent or diminished in some SF movies. Given how far CG critters have come, I bet the Moties could be quite convincing.
And besides, it would be so frickin’ nice to have a SF movie featuring aliens that don’t roam the galaxy looking for humans to kill. 
Anne MacAffrey’s Dragon series. Okay, so it’s not really science fiction, but give the lady a break. It’s a doozy of a tale, lots of action, good characterization, and CGI is finally at the level where it could handle the dragons and Thread.
As I implied in another thread earlier today, I’d really like to see A Canticle For Leibowitz adapted for film. (Preferably as the Next Big Trilogy, since the novel is divided into three discrete ages.)
It’s my favourite kind of futurist writing in that it draws on a deep understanding of history and is as much about the problem of being human as anything else, like all the best tales are. (“No new thing under the sun.”)
The post-apocalyptic thing always gets the crowds in, and the ideas in novel are really profound, if a little bleak. The veneer of Catholicism would make for nice visuals, on the most superficial level. A religious order preserving technology that they don’t really comprehend, which contains power that is both nourishing and potentially destructive. Their earnestness. The grim practicality of the warlords that hold the “real” power. It’s all timeless.
That scene where the archivist is robbed by mutant highwaymen on his way to take his illuminated diagram to the Pope? Cinematic gold. I can see his relief and disbelief when they toss aside the real treasure and take the shiny thing.
Properly made, it would please everybody. The technophiles, the mystics, the history buffs, the kids who just wanna see people killed onscreen. (I guess it lacks sex, but whaddya want?)
I’d like to see a movie based on Neal Stephenson’s Snow Crash. An exciting story, plenty of opportunities for special FX, and the vision of a future America of politically independent suburban enclaves is really thought-provoking. Also The Diamond Age – nobody has made an SF film yet about the social implications of nanotechnology.
A movie (better still, a miniseries) based on Robert Anton Wilson and Robert Shea’s Illuminatus trilogy would be totally awesome! And rather topical, especially now. “It was the year they finally immanentized the Eschaton . . .”
I’d like to see Frederik Pohl’s Gateway turned into a movie. The follow up novels can be ignored, for now- but the idea of strapping yourself into an alien ship with as much room to live in as a standard closet and flying into the unknown for a chance at riches- future reality TV material! Especially the relaxed sexual mores on the threes and fives.
The cool thing is that the technology is never really explained, so the audience shouldn’t be lost in technobabble. All the tech that the protagonists use (other than the ships) is man-made, and nothing too advanced.
It would be best done by an indie company. The lead needs to go to someone who can show the neurosis that creeps up on him during the story.
Lord Valentine’s Castle by Robert Silverberg. I’d love to see the metamorphs. And the juggling!
And Ric Flair could play F’lar.
Heh. FNORD
(Not to mention GWB-666 humming away in the Pentagon, providing narration.) 
FNORD
There are periods of history when the visions of madmen and dope fiends are a better guide to reality than the common-sense interpretation of data available to the so-called normal mind.
Another vote for this one. I really have no idea who I would like to see in the leading roles but have read the entire series and always thought how much I would like to see this on film.
Asimov’s Foundation series. Neat plot with a grand scope, based as it is on the fall of the Roman Empire.
Forward’s Dragon’s Egg. I’d love to see the neutron stars aliens’ society advance over the course of a few days.
Niven’s Ringworld series. Opportunity for great special effects of the Ringworld.
Zelazny’s Amber series, except it’s not SF. Opportunity for sword fights and battles, plus I’d love to see the Trumps and shadow-shifting visualized.
l’d also love to see a movie based on Heinlein’s Starship Troopers or Asimov’s I, Robot. It’s a shame no filmmaker has ever tried to make a movie that had any relation to these books beyond the title. 
P.S. I second the recommendations for both MacAffrey’s Pern series and Silverburg’s Majipoor books.
JC & Moe
It’s set about 500 years in the future. Humans have pretty much moved out into space, and they’ve found a huge, abandoned spaceship in the asteroid belt. Then the descendents of the owners show up looking for it…
I’d like to see it as a movie because it’ll mean I’ve finally finished the blasted thing. And I’ll probably have a better title than “JC and Moe” by then.
I wonder why more of Heinlein’s work hasn’t been adapted to the big screen. Several of his novels seem like naturals.
The Moon is a Harsh Mistress. I imagine a detailed depiction of the living arrangements and the society of the moon. I’d probably talk to Paul Verhoeven about directing, but I’d want some assurance that it would be more like Robocop or Total Recall than Showgirls. This book has a good balance of action and plot. For some reason, I imagine Seann William Scott as our leading man. (Don’t hurt me.)
Glory Road. Why isn’t this a movie? Adventure and magic and beautiful women…and some most unexpectecd plot twists. It would be a perfect action/fantasy/comedy. Angelina Jolie would be our leading lady, even though she’s not a blonde. Our leading man? One of those hot young actors that everybody gushes about but I can’t tell apart…
Methuselah’s Children: The premise is just really interesting. And Lazarus Long is just cool. I can’t imagine who could do him justice. Unfortunately, I can’t stand Sean Connery, but he might work in the role. And of course, if the movie is successful, the makers could move right along into Time Enough for Love.
p.s. I see on preview that robby’s beat me to the snarky comment about Starship Troopers…
Spider Robinson’s Stardance. It’s got it all: dance, music, space stations, aliens, and sex.
I’d love to see a film version of John Wyndham’s The Kraken Wakes, if only to see the scene where the sea-tanks attack the town of Escondido, “trawling” for humans.
Frank Herbert’s White Plague
Not only is it topical (terrorists, genetic manipulation, stem cell research), but it is quite an exciting story.
Sure, most of his works don’t translate out of printed form very well, but I think this could. It’s got very few main characters (compared to most of his stuff), so we could get into the story rather quickly.
And what a story! Terrorism, world government (of a sort), war, political/religious/courtroom drama, sex, insanity, intense love, plus a perfect role for Johnny Depp (Joseph Herity).
If not that, do Whipping Star. I want to see Bruce Willis in sniggertrance.
I’ve written on this many times on the Board. But here goes, again:
I’d like to see Alfred Bester’s star novels, The Demolished Man and The tars my Destination filmed. I think Stars has one of the best damned openings ever – Gully Foyle, barely surviving on his ruined spacship, sees another ship approaching, fires a flare, knows that they saw it and then they turn away and leave him. The act gives him the impetus he needs to survive and to chase them down. Properly done, this is a killer opening. I’ve always wanted to portray the “jaunting” society, and he blazing climax would be imressive. I also think that the telepathy sections in Demolished could, in the right hands, be visual poetry. In the wrong hands, it’ll look like cheap Movie of the Week.
But I think that it’s probably not a good idea to pursue SF novels. There are often so many ideas that have to be introduced and explored properly that you’d need an excessively long film. Look at what happened to Dune. Can you really think that, say, Ringworld will fare any better.
It’s a better idea to take a short story or novella and to use the time you have to fully explore it. Personally, I’d like to see Arena filmed right for once. I’ve been filming it in my head for years. I ouldn’t mind seeing some of the great short SF stories from the 1940s and 1950s done. Twilight Zone actually did this a lot, you know. But today we have the CGI to llow us to get away with a lot, visually. Some choice Fredric Brown, Heinlein, Asimov, Clarke, Tenn, Sheckley (done right, for once) , or any of a number of others. How about de Camp’s A Gun for Dinosaur (Or is that a little too much like Jurassic Park?)?
How about Asimov’s Nightfall, done right for a change?
And while we’re at it, note that some good SF films came from short stories – who’d ever think that Harry Bates’ “Farewell to the Mastr” would ever make as good a film as The Day the Earth Stood Still?
Since the Bush Admin has talked about a manned mission to Mars, I think a movie based on Ben Bova’s Mars would be very timely.
And a movie of Arthur C. Clarke’s The Fountains of Paradise (which I haven’t read, but I know what it’s about) could help publicize the “space elevator” idea.
I would suggest Niven and Pournelle’s Lucifer’s Hammer, but since we’ve already had Armageddon and Deep Impact . . .
Shakespeare’s The Tempest would make a good Sci-Fi flick.
You really want Verhoeven behind another Heinlein movie? You can say what you want about Starship Troopers, but the one thing it was not was a faithful re-creation of Robert Heinlein’s book. It’s practically a parody of it.
Anyway, back to the OP, I’ve always thought C.J. Cherryh’s Finity’s End would make a great YA movie. I actually see it as a Disney TV movie than a theatrical release. It’s basically about being a teenager and the feelings of alienation and powerlessness that entails, and trying to come to terms with a family that you didn’t know you had, and don’t necessarily want to be a part of. With spaceships. Not a whole lot of special effects, lots of good characterization. A good cast and some cheap CGI, and this could be really amazing.