Being a Halloween lover, I have also always loved Halloween music, or music that is otherwise spooky or somewhat gothic. Years ago, I discovered two very cool sources for this type of music, technically called Gothic Horror Soundtracks. The first was Midnight Syndicate (www.midnightsyndicate.com). 'Midnight's" music is used at many professional haunted attractions, and their cds can be found at some Halloween stores such as 'Spirit Halloween.' I believe they can also be ordered through amazon. I currently only own 'Gates of Delirium' and 'Born of the Night,' but they've come out with many more since then. Their music is perfect for any Halloween yard haunt, or if you're simply in the mood for something dark and ethereal.
The other one I came across is Nox Arcana. (www.noxarcana.com) Like 'Midnight,' Nox Arcana's music is also used at many haunted attractions. I think I might like their music slightly more than 'Midnight's,' although it would be hard to choose. I only own one cd by these guys, 'Winter's Knight.' My fave track is Ebonshire. It is so beautiful, and is such a haunting melody. To hear samples of this album and more, check out the site!
The last one I'll mention right now is a group called 'The Changelings'. I first heard of them when I was reading about Anne Rice's vampire ball back in the '90s. This group played live at the ball, and was a big hit. (www.changelings.com) They have a very unusual sound, and the female singer's voice is beautiful. They would be great to play at a Halloween party.