Here's a second for LibraryThing, which allows you to review or comment on books that you list within your library. Plus, I find that its list of recommended titles, based on your library, is quite accurate and helpful. In addition there's a book giveaway feature with a number of titles both from traditional publishers and self-published authors.
My novels, Valentine's Cafe, Thereafter, Darkest Desire: The Wolf's Own Tale, and Mermaid in Vegas are available at Amazon
. Blog: Books and Boats.