I've just stumbled across Steve Clayton's BookRabbit - Facebook for your bookshelf post and given it a whirl for myself. I don't use much paper at all but like Steve I do still enjoy reading good books. BookRabbit is cool as not only can you easily browse the book shelves of your friends, you can see who's reading books you rate highly - this gives the following benefits:
There are video interviews up there for some of the books too.
For the site to live up to it's possibilities I strongly encourage you to take a picture of your bookshelf (or part of it) and upload it to the site - I'm going to do mine tonight all being well.
Something else that's really cool is you can easily buy books that interest you and many of them are discounted.