Goodreads is a social network for book lovers — a place to tell others what you’ve been reading and find great recommendations.
You can look up books that you’ve enjoyed and see other related books that readers enjoyed, along with lists that people have created that contain the book (and other related books). If you’ve got the empty feeling after finishing a book and don’t know where to go next… this will help.
It’s possible to track your progress whilst you read and then provide a rating and (if you like) a review once you finish. This means that every book has a rating, which can be helpful when choosing a new book. Ratings don’t mean everything, of course… but I’ve not yet had a bad experience with a highly rated book from Goodreads.
I don’t use it religiously, but I do check it out when I’m in need of reading inspiration. It’s well worth a look.