On the left sidebar I have a “chiclet” that will link you to an online catalog of the books I own. A few of them have ratings and reviews attached to them, and I am working on updating the rest of them as well. This is my most favorite book related website. It has a wide range of versatility (and constantly expanding) for those who want to keep an online list of books. Some use it for their physical collection of books (as I currently do) and others use it as a reading list, and even others use it as both via the available tag system. Additionally, the creator keeps promising a collection system to be put in place to make it easier to separate and differentiate classes of books such as those owned from those only read.
Another great aspect of this site is the numerous chat groups that are available that allow one to interact with other readers and discuss books, authors, and anything else. I have found that there is a good mixture of groups that allow in-depth discussions as well as some that possess a lighter more fun-based attitude. Either way, it is a good place to give and get suggestions on good books to read.
It is impossible to list all the aspects here, so if you enjoy reading, or just talking about books, I suggest you go to www.librarything.com and check it out. You can take the tour before you decide to join. And signing up is totally easy. All it requires is a username and password. From that alone you can enter a certain amount of books for free, or if you want you can get a lifetime membership for a low one-time fee and enter an unlimited amount.