Discovered Goodreads last month and am very jealous, I wish I had made a website like this. Actually they do have millions (well, lots) of people writing for it, so I have no chance of emulating it.
Anyway this is a great website and worth looking at. You can rate the books you have read or create a would like to read list. You can also see what your friends are reading and how they have rated the books. There are also lots of groups to join or quizzes to do. I have also been looking at their worst books of all time list, for some inspiration on my next post about rubbish books and there are some controversial choices in there like Animal Farm and Tess of the D´Urbervilles at 28 and 30 respectively. Despite this travesty it is still a little bit addictive.