With supernatural, spooky sounds being a musical trend at the moment (a trend that long preempted the Halloween season), there are lots of dragged out, slowed down remixes of tracks that are just plain bad. There's not exactly a high barrier to entry for simply slowing music down.
On some rare occasions, slowed down, eerie remixes can be done right. This is no witch house track, but it does feel chilling enough to suit the season. Deep house DJ Urulu has given a slow, subtle, longer treatment to psych-folk outfit High Places' track "Dry Lake" and it's real slick, blending danceable percussion and reverb with the eerie female vocal to create something awesome and unique. You'll have to listen to this one more than once to take it all in.