Now this is an application I really like! I look forward to exploring it more and have added it to my iGoogle desktop. It is certainly useful for my own reading - 20 others have posted about the book I'm currently reading, and I found out more about it. Recommendations of similar books flowed as soon as I added 3 books in one of my favourite series to my library collection. I intend to investigate adding it to the OPAC at my work library, and to the library website (under construction).
I keep a paper list in a notebook of the books that I read - now they can go into the 'Read but unowned' collection on Library Thing.
Being a member of a group of like-minded people is reassuring - being an adult who reads predominantly YA books often puts me in a group of one in face-to-face discussions. My Library Thing catalogue http://www.librarything.com/home/fondofbooks is still quite small, but give me time.