Bookshelved [http://bookshelved.org/] is an active and growing wiki about books, for everyone with a passion for reading the things. With over a thousand pages, there's something for everyone.
By convention, each WikiPage on Bookshelved is the title of a book, the name of an author, or the homepage of a reader.
A candidate for addition to this wiki's SisterSites (search for "BookShelved" on WardCunningham).
note of concern - the site's been down for a while. In a world now glutted with "social media reviews", we need our lean & non-commercial pioneers back!
I found http://bookshelved.org/cgi-bin/wiki.pl to be up, running, and active ( with several participants during the last 30 days ).
It has over 160 names in its Visitor's List, found at: