After GoodReads sold out to Amazon, in more ways than one, I cast about for alternative book sites and came across an interesting one, still in beta at the time, called BookLikes.com.   One of the things I like about it is it has more of an international flavour, which is not surprising because the people who created it are in fact all Polish!  Despite which, they're very much centered on English language books and link through to B&N, Amazon, and Powell's.

Creating an account not only creates a GoodReads-like bookshelf and follower system, but also creates your own blog under their domain, that's accessible by the whole world.  So if you want a free blog that's book-oriented, then it's sort of a natural.  I don't use it that way because I have my own very lovely blog, but I can see where someone might find that useful.