Open Library, a project of the Internet Archive, is a site with a web page for every book. It strives to become a wikipedia of books. 23M books, over 1 million free ebooks, wiki editable, completely great.
A new version of the site is now offered for public testing on upstream.openlibrary.org. For the new features please see the announcement.
Congratulations to the Open Library redesign team: George Oates, Anand Chitipothu, Edward Betts, Lance Arthur, Karen Coyle, Winnie Chen and many others.