Nox Arcana and Midnight Syndicate do a bunch of the kinds of music that you hear in haunted houses. So, it's certainly dark, but a bit on the melodramatic and predictable side. Perfect for background stuff, but if you actually stop and listen to it, it'll probably put you to sleep. I most recommend Nox's Transylvania, The Necronomicon, and Grimm Tales, and from Midnight Syndicate, Vampyre is my favorite--although The Dead Matter (Cemetery Gates--not to be confused with the other Dead Matter which is the soundtrack they did for some b-movie) is really good too. For that matter, both have recently released or are about to have released a new album for the 2011 Halloween season. Can't comment on either yet.
The Wolfman, the newish soundtrack by Danny Elfman, is one of my favorite creepy soundtracks lately, but it's definitely got a Victorian horror vibe to it that might not be perfect for modern horror a la Hunter.
For that, I'd maybe look up the soundtracks for Constantine and End of Days. Those are my go-tos for "overtly creepy."
Dracula and Sleepy Hollow are both pretty good, but you might want to edit the tracklist; they've both got a few "romantic" themes mixed in with the darker "horror" themes.