Finding similar books by author, genre and subject?

Some time ago I stumbled up on a web site that had a novel and fantastic method of recommending book sand authors. You simply typed in a list of authors you had previously enjoyed, and the site constructed a spider-chart of similar authors. The closest matches were near the center, with close, but less similar authors being placed further from the center. I sure wish I could find that web site again... A variety of google searched didn't turn up the site I was looking for. Thanks for the assist, folks.