I'd like to see some of Iain M. Banks Culture novels turned into films, as they've always had a cinematic feel to them, to my mind, but I suspect they would lose a lot in the translation.
Also, I'd like to see more good adaptations of John Wyndham novels (if they are like Triffids was at Christmas though, you can forget it!).
A period adaptation of War of the Worlds wouldn't go amiss, either.