It'd be cool to see someone make a horror movie inspired* by the Titanic. Those pictures of the corroded, submerged wreck with those doll heads and empty shoes strewn about are creepy enough; throw in some restless Poltergeist type entities and you could have something really horrifying on your hands.
*Yes, I said inspired by, not based on, so don't start pissing and moaning about me being heartless and insensitive towards the survivors/victims of the real-life event, okay?