Got a bookshelf on my blog now. :) Scroll down, on the left there. It's a pretty cool widget! And very simple to stick on your blog.
You can add as many books to your shelves as you wish, sort them by:
Books I've Read
I'm Reading This Now
Books I Plan to Read
You can easily move them back and forth from category to category as their status changes. You can mark some as favorites. You can rate them, one to five stars. You pick what books will display on your blog - I decided to have a 4 book shelf, with 4 top favorites showing.
Click on my shelf, and it'll take you to my profile, showing you all the categories, the 50+ books I have on there. Hover your mouse over a book on the shelf, here on my blog, and it gives you the short review, plus a button where you can add it to YOUR shelf, and put it in the 'Books I Plan to Read' category.
Once you have some books on your shelf, you can (if you choose to) hook up with other people who read what you do. The site is filled with book clubs, some divided geographically, some by genre, some by common interest, like Mommies Who Read. Each book club has a bulletin board to post on.
No affiliation to Shelfari here, just thought it was a neat idea. And I'll be looking for bookshelves on others blogs, to see what YOU read!