I love LibraryThing, it's so much fun and another treasure trove of a website. I had created an account before starting web 2.0 as one of my colleagues told me about it. I have been slowly adding more of my books to it and I love seeing them all on my virtual shelf. My favorite mark of the site is how they display all the different covers and people can upload more. As two of my main passions are art and books I love looking at all the differnt covers, how differnt people have seen the book and how they have changed over time.
The interaction with other people on this site is great, through forums, reviews and the cool feature of finding people with the same books as you. The reading suggestions are also very good. The only complaint I have is that often the search brings up very poor results and the book I want is often not on the first page.
I am very excited about the possibilities for colaberation with libraries, as the visual and interactine acpects of this site are very cool.
The link to by catalog is here, hopping to add more soon.