... you might be interested in Booktribes, a social networking site for book lovers.
Registration is free. You start by entering the title of a favourite book. This connects you to other people who like the same book and you can see what else they enjoy.
You get your own profile page and can post review as well as join discussions.
Sort of a high-tech online reading group with lots of different titles at any one time.
I'm having a bit of trouble finding enough time for breathing at the moment, so I won't be playing, but thought others might find it useful.