OK, some great suggestions, and some not so great suggestions out there.
Riftwar would be Awesome, and the Kelewan series would be every bit as good.
Enders game, while superb as a book, is going to lose almost everything that made it worthwhile as a movie. Sorry, but scrolling the cinematics of the book through my mind, I realize that most of what makes it a great book is all going on in Ender's head. Still, we'll see.
Hear hear to the Running Man made right! But it'll be years before anyone would believe that someone would fly a plane into a tall building just becaus...
Nevermind.
Wheel of Time, Dark Tower, Song of Ice and Fire, Belgariad are all too long to be made into decent movies. The same, I think, with Memory, Sorrow, and Thorn, a favorite of mine.
Moon is Harsh Mistress (as Manny would call it) is every good book, but world is not ready for ideas yet. Give 10 years, 15. Am <i>bolshoyeh</i> certain screen writer would do worse to <i>gospodin</i> Professor than putting him out airlock. (I really love that book. I don't think they could do it right.)
Thomas Covenant. Hmmm. Now there is a set of books crying out to be a movie. It one of the ideal situations - a dreadfully written book with exquisite characters, settings, and ideas. With the right screenwriter and special effects people and actors (Jeremy Irons as Mhoram? Ed Norton as Thomas? Picking a Bannor and a Foamfollower would be key. Ditto Lena) it could be an improvement on the books.
While I'd like to see a Terry Pratchet book turned into a movie, I think one of the more ridiculous ones would be better. I would be worried about what bad things could happen if they did Colour of Magic or (my favorite) Small Gods.
According to web scuttlebut, Miramax has optioned His Dark Materials, a Theatre in England is going to do a stage production, and the fellow who directed road to Perdition is interested. It could happen. Think the Jesus Freaks went apeshit over Harry Potter? You ain't seen nuthin' yet. For no other reason this should be made into a movie.
I would love to see any of the Greek or Roman war classics made into a movie a la Gladiator/LoTR.
Now, as for my picks:
Terry Gilliam has said that he would love to make a movie out of "The Watchmen". He has also said that, in order to do a good job of it, it would be about 12 hours long. My personal bias is that he could do it in half that without too much drop off in quality or trimming of sub plots. If for no other reasons then that first scene where Rorhsach's alter ego is trooping through the Comedian's blood and because I'm dying to see how he would work the scenes where the history of Dr', Manhattan is interleaving with the present and the "Black Freighter" comic that the kid is reading at the news stand.
My all time favorite movie project, though, would be Zelazney's Lord of Light. They are just now to the point where the required special effects are available.
<a href="http://www.cinescape.com/">Cinescape</a> has a pretty good site for checking out this kind of thing. Unfortunately, it's really frickin' slow this morning, or I'd link in a couple of things.