American Gods by Neil Gaiman has the potential to be a great movie, but pulling it off would be hard.
I'll back the idea for Ender's Game, though, again, hard to produce and I don't know that it would come off with nearly the same feeling as the book.
And what does anybody think about making a movie based on The Satanic Verses? I think that could go places if they got the right director... Then again, it has the potential to go completely haywire as well.
And I'm waiting for Halx to write a book based on everything that happens here on TFP so that the movie can get kicked into production as soon as possible.