Goodreads - Simply Amazing
Goodreads is one amazing site. If you haven't checked it out yet, you should go do so now. Its is absolutely amazing. It lets you create your own profile, on which you can add friends, books you're reading, books you're wanting to read, books you've read, and so much more.
Not only can you add everything about the books you want/read/reading, you can also add your favorite genres and authors.