There are lots of book-related sites on the web, here are two of my favorites:
Paradoxically by Paradox Olbers
In my first blog I mentioned a SciFi-guru friend of mine: this is his page. His name is Spike MacPhee and he was the owner and manager of the Science Fantasy Bookstore in Harvard Square in Cambridge, MA from 1977-1989. Toady he is deeply involved in Second Life, managing his own virtual gallery of astronomical art; he is a head of operations at the International Spaceflight Museum, as well as a NASA Second Life CoLab manager. So he knows whereof he speaks. His blog has a wealth of information on Second Life, science and technological news. It is also a trove of reviews and essays about science fiction, both classic and comtempary.
The other site is Shelfari ( http://www.shelfari.com/ ), a clever little social network based around books. Members fill virtual bookshelves with chosen books, rate them and/or comment on them. Then you can find other members who share your tastes, join discussion groups, browse your friends' shelves, and talk books to your heart's content. It's easy to use and fun, just be careful during registration not to invite your entire email address book (the site's default setting).