There's a few things I would like to see there. It has an option to produce a box featuring selected books to display on your site, but doesn't have RSS feeds. There's no standard way to indicate books that you are currently reading, but you could use a tag for this. It allows for linking to books with an Amazon associate ID, but I think this is only for the US site.

I noticed today that I had a message in my guest book from the owner of Library Thing, Tim, in response to the previous entry asking if I had seen his site. We exchanged a few emails where I told him what I think. He intends to take some of my suggestions on board. He's charging a small fee for those with large book collections, but will probably not get rich from it. I told him that I really appreciate the efforts of people like him in providing such services. The next time I have some spare cash I intend to make a few donations to the sites whose services and products I regularly use.