If anda are an avid reader like me (I'm bookaholic) certainly you'll enjoy these places.
The Shelfari is the best place to tunjuk off my books, the favorites, the owned, the wish, the must read ones, etc. There are interesting groups and anda can connect with people all around the world just like you. The shelfs can be displayed in your blogs, journals atau sites.And it's all for free.

The perpustakaan Thing is a very good site too, but for free anda can catalog only 200 books. In the order hand, perpustakaan Thing have a great BookSuggest searching that can recommend anda a book from a book that anda already read. It's very helpful.