The OpenLibrary collection
As stated on the OpenLibrary about page on 2009‒04‒18
One web page for every book ever published. It's a lofty, but achievable, goal.To build it, we need hundreds of millions of book records, a brand new database infrastructure for handling huge amounts of dynamic information, a wiki interface, multi-language support, and people who are willing to contribute their time, effort, and book data.To date, we have gathered about 30 million records (20 million are available through the site now), and more are on the way. We have built the database infrastructure and the wiki interface, and you can search millions of book records, narrow results by facet, and search across the full text of 1 million scanned books.
We are not sure when a more recent version of the data will be available.