The ultimate book recommendation site. I guess this is more of a book sharing social network than anything else. You can get recommendations from other readers, keep track of what you have read and even play book trivia, if you are really a book geek. What you do is browse through what others are reading (and enjoying),  check out their own reviews and even join in any discussions regarding the books. Not to mention, they have also collected tons of information on books like date of print, author profile and awards the book has gartered. Useful website even for those who are not geeks.