As luck would have it, Tara Maya pointed to a beta site called "Book Country", created by Penguin.
Book Country's tagline is "A Place to Discover and Share Fiction".
What's the most interesting and innovative feature of Book Country? Why, it's the ability to find genre-mixing books! Take a gander at their genre-mapping page, and pick your favorite genre. Then click on the "Select Genre" button in the pop-up box. See that Myers-Briggs chart, the one you roll your cursor over to find sub-genre and cross-genre books?
Folks, it's official. The world is no longer flat.