Library Thing is the global version of the catalog's My Discoveries.
If you create a Library Thing account you can then write and participate in all of Library Thing's features.
You can -
see and write ratings and reviews of the title
view and participate in interactive online conversations
view and create weighted tags to find other titles that use the same tag
see a list of "if you liked this book, try. . ."
view common knowledge that provides information about the book's characters, locations, favorite quotations, bloopers, etc.