Hey, this was fun! I put in "Deep Naked" (paranormal/sci-fi) and the "most similar books" button brought up books by Terry Brooks and John Flannagan.
"Split River" (mystery/suspense) brought up Anna Godbersen and Adrian Tchikovsky (sp) as most like it.
Both books brought up "Bright Young Things" by Anna Godbersen as being most like them (the books). I never read that book, but I saw the film and was really creeped out by it. I find this interesting because the books I input are two different genres. Also, both books came out high on "Historical Romance" and neither book is supposed to be that.
"Burn Pile" most like it was George RR Martin. I also came up with Stephen King on that one. I got Thomas Harris and Mario Puzo on the "books like it" button. Harris' book "Red Dragon" (intro to Hannibal Lector) starred all the way across in terms of similarity. I had to read part of his book to make sure he hadn't copied me.
Oddly, I published this book in genre "horror" and it turned out on this tool to be "fantasy."