Hell, why not make The Hobbit? He'd already have some of the characters from Lord of the Rings, such as Bilbo, Gandalf, Gollum and Elrond. I mean its in this story that the One Ring makes its first appearance and it would make sense to make this film.
Alien, I'd love to see a new Alien film but with decent directing. The last two were imo crap, the first two were brilliant. I don't think it needs a re-make and I don't think the series should coninue unless they get a first clas director to continue it, they ruined the Alien saga with Ressurection.
One I'd really like to see is "The Day the Earth Stood Still". I've read the original short story it's based on, and it'd make a terrific film, sans the cheesy effects and add ons given in the movie. There are some great action sequences in the original story which I think Peter Jackson could do justice.
I've just thought of a few more (hell, maybe shouldn't have made a poll at all). Starship Troopers was a kick-ass book. The movie didn't have even one tenth the depth of the book.
Like Golem? Or half the shots in LOTR? Come on. Granted there were some really ugly shots in King Kong, but there were some incredible shots as well. Just as all movies that incorporate a decent amount of CG.