I unequivocally love Goodreads. I’ve been using it since 2008 and of all the “bookshelf” websites, it is by far my favorite. It’s an excellent way of keeping track of your own reading, learning about new books, and connecting with other readers. It also has a number of great uses for libraries.
At the culmination of it’s fifth year of existence, the Goodreads blog posted a neat infographic of 2012 use.
P.S. If you have a Goodreads account and would like to add me, I’d love to be friends.