1. Avatar: Seriously, can't you imagine some sci-fi author writing this as a super-long trilogy thingy that everyone avoids because of shear length, only to jump on the bandwagon a month before the second book comes out, just because the popular people claim to have read and liked it. It would so be one of those books. And movie rights would totally be optioned, but never used.
2. Labyrinth: The only reason this would be good as a book is that it would be less ridiculous. No one wants David Bowie to look ridiculous, so making it into a book might make people believe that it was made after what is sure to be a funny-in-a-sad-kind-of-way, oft-made-fun-of, frequently-discussed book. Come on, who wouldn't read that?
3. Ultraviolet: I had to include something involving vampires, and besides, Garth is hot shit. I dig sexy nerds, especially when they have those
4. Pirates of the Caribbean: Jack Sparrow is awesome. They could write an entire series of 200-page even books on him, spitting out one a month. Like the novel version of a comic book, sort of. To pull it off, though, they would have to change Orlando Bloom into a blond, with pointy ears. That's what the female fans want, and after seeing how well the Lord of the Rings books did, who wouldn't want to get a little of that Legolas action in their books?
5. Push: The token cliched awesome-power people. Nuff said. PS, Dakota Fanning was really good in this movie!