As I type, my action/suspense story, "Island Ghosts", which previously appeared in an anthology of hard-boiled detective stories (even though it doesn't feature a detective) is #3 on the free horror bestseller list at Amazon. (Who ever said genre classifications aren't malleable?) It's also #73 out of ALL free ebooks at the store.
(Actually, the main character is a "slightly psychic" U.S. Marshal who becomes a paranormal detective in future stories, plus there's a hint of ghosts at the end of this tale - and more than a hint in subsequent tales - so Amazon's classification probably applies.)
There are also two more stories out there featuring "Island Ghosts'" protagonist, Will Castleton - "The Bridge" and "Samantha", with another, "Nighteyes" coming in the next week or so.