Lot’s of good suggestions here, but how about Hyperion and Fall of Hyperion? I doubt anyone could do it justice, but I have always wanted to see it made.
Funny you should mention that…
Water for Elephants by Sara Gruen
Good Omens has already been mentioned, and I’ll add Guards! Guards!, the best start for a big-budget Discworld series, imho.
I’ve also thought that the first few of Elizabeth Peterson’s Amelia Peabody books, starting with Crocodile on the Sandbank and ending with The Snake, The Crocodile, and the Dog would be a great BBC series. Adventure, mystery, romance, period archeology…
Now, what do you think the odds are they do it well?
Looks like the director and the writer are both pretty inexperienced with feature films. That’s unfortunate, as I think the story deserves much more than that. But, being an early feminist screed that’s been relegated to the annals of first-semester American Lit, I guess it won’t get it. 
That said, it’s possible that these guys will bring a lot of passion to the project. We’ll just have to wait and see.
Simon Birch scratched the surface of A Prayer For Owen Meany to the same degree that my cat scratched the surface of Snow Crash, rendering it into a worthless pile of confetti.
…and I would like to see the three discrete parts of Walter Miller’s Canticle for Leibowitz made into the Next Big Trilogy. (Please!)
1.- Tunnel in the Sky by Heimlen. It’s the perfect book for a movie adaptation any idiot (except Verhoven) could write a decent script without needing to rewrite too much.
2. Nine princes in Amber could be a decent trilogy.
I was surprised that Isaac’s Storm by Erik Larson (about the 1900 Galveston hurricane) was not made into a blockbuster movie in time for the centennial anniversary. Great story elements apart from the effects of the storm itself.
It’d be a tougher proposition now, what with recent events (foretold in the book).
That’s a bit like saying the Lord of the Rings books are a remake of one of the D&D Forgotten Realms trilogies. Or more appropriately, that’s like saying the Peter Jackson Lord of the Rings movies are a remake of the Dungeons and Dragons animated TV show from the 80’s.
The Matrix is a by the numbers, derivative, Hollywood turd dressed up in pseudo-intellectual masturbation that sounds suspiciously like the silly ass philosophical and film-critic eructions of couple of geek-lite freshmen laying on the floor, stoned off their ass.
Neuromancer, on the other hand, is a fun bit of well crafted entertainment.
Time to seek cover before the flying Keanu Reeveses descend.
Seconded! 
In all seriousness, I think that a well-done adaptation of Neuromancer would be great, but I doubt it will ever happen. Now that we have The Matrix, any attempt will just be seen as a ripoff of The Matrix. It’s a shame, but that’s reality. As time goes on, we’ll forget The Matrix, but it will be harder and harder to do Neuromancer without making it look like an outdated 1980s pipe dream. I mean, look at how much Shadowrun and Cyberpunk have changed.
I know you’re right. I just wanted to go on record with my seething hate. The creeping obsolescence is why I need the $100 million now!
Shade’s Children: This is kinda of a tweener book that’s between ages 10-18 or so. It was one of my favorites in my younger days and I thought if it was done right it would be an AWESOME movie.
Basically it’s a post apocalyptic story of a group of refugee kids with special powers who fight these evil knight-like things that have taken over. It would have sci-fi action, great visuals, and even more than that…great twist at the end.
Anyone else read this and can maybe back me up?
I would like to see The Space Merchants made into a movie while it’s still science fiction.
I would make a TV series, on the Sci-Fi channel, of Zelazny’s Amber series. And cast it with TV actors, not movie actors. In particular, I think John Barrowman would be a good Eric, because Eric doesn’t appear much; he’s mostly referred to by other characters. So when he is shown, it would be good visual shorthand for him to be the obvious hero type, thus justifying his brothers’ resentment of him. (Even Julian and Caine don’t seem to like him much; they’re just backing the winning horse.) Other than that, I’m not sure, except I think Tricia Helfer would be an effective Llewella.
Ender’s Game is supposedly in the works and I’m hoping it will be good.
The Dark Tower series done as a long, slowly developing character study on HBO. Perhaps a 20 hour miniseries or something. They can scrap all of Song of Susannah to squeeze it in. Perhaps write out the Steven King character too. With J.J. Abrams supposedly putting it together it might have a chance of being decent if a network is willing to give them enough airtime to do it justice.
American Gods could be a challenge that’s worth doing.
I love the idea of Pixar doing Watership Down.
How about Niven’s “Not long before the end” as an animated short?
Yes, yes, yes, yes, yes, yes, yes!!!
Burroughs’ A Princess of Mars - Actually in the works over at Pixar, I have heard.
Gaiman’s American Gods
A decently-budgeted version of Gaiman’s Neverwhere
Stephenson’s Snow Crash
Peter Mattheison’s Far Tortuga." It’s about a group of turtlers in the 1970s coping with modern pirates, the decline of the turtle fishing industry and one hell of a storm. It would make one hell of a movie. And that description is so flat and dull that it’s completely inaccurate, even though it’s factually accurate. Read the Amazon.com reviews (for some reason the url wouldn’t copy, so I did the NY Times review from 1975 instead) to get some idea how good the book is. Done properly it would be THE movie about the sea – there simply would not be any point to making other movies about the sea. And with all the talented black actors we have nowadays, it could definitely be done properly.