I love LibraryThing! As yet I have only created a small personal library as I need to convert my written reading records gathered over many years of English teaching and teacher librarianship. This will be a school holiday project - but at least I am underway.
I love the ability to share reading, to quickly have suggested supplementary titles and authors and to be able to assign real - person tags, rather than restrictive and not instinctive formal subject headings.
I have set up my school Bookclub students in a closed room and we share our reading between meeting times.
I am in the process of considering incorporating LibraryThing into our LMS but there are compatibility issues to be sorted out - a work in progress.