The Devil's Backbone (Guillermo Del Toro, 2001)
I enjoyed this quite a bit. The story is a little predictable, but the execution is what really matters here and it's excellent. It is a nice companion piece to
Pan's Labyrinth, and like
Pan's, the supernatural / fantasy elements aren't really necessary, the story is really strong without them, but they add layers to the movie and give it a strong identity. I also really loved the visual cues of the ghosts (the underwater look, and the flies later). I wouldn't really recommend this as a great ghost story, but as a great story with ghosts.