Roadside Picnic, Metro 2033, and Mortal Engines.
Roadside Picnic is a horror/sci-fi novel where the Chernobyl incident is actually caused extradimensional aliens dumping their stuff in our world, which caused tons of weird and spooky stuff popping around the area. It's already adapted into videogame (the S.T.A.L.K.E.R series). The game is good and it would make a good movie in my opinion.
Metro 2033 is a post apocalyptic adventure novel about Moscow after a nuclear war, where people lives in the tunnels of the Moscow metro, while all sort of scary things walks about on the surface and in the darkness. The author spends a lot of part of the novel building the overall setting and atmosphere of the world, which would make adapting it to a movie easier.
Mortal Engine is a steampunk adventure novel in a world where all the resources have been completely dried out and now cities turn themselves into giant tanks that eats each other, literally. It have an interesting setting that would make a great movie series.