I first heard of this useful website through the July issue of the Discworld Monthly e-newsletter.
Book Drum offers a way for readers to read or contribute "Profiles" of books. These consist of several features, including a summary, setting information, glossary, author information and reviews.
The most exciting feature is the "Bookmarks". This is a collection of multi-media annotations for the book, utilising text, photos, maps, and even music, sounds and videos to explain and clarify the text.
As of yet they have fewer than 100 Profiles posted, but thanks to a dedicated group of users you can expect it to grow continuously. Anyone can register and contribute a profile, and once a profile is published, other users can add to it.
So, Dear Reader, do pay it a visit. Read it and spread the word, even register and add a profile. I plan to register myself and test how easily the profiles can be posted and added to. Expect a review when I have become fully acquainted with it.