OpenLibrary.Org

Here is what OpenLibrary.org says about itself:

One web page for every book ever published. It's a lofty but achievable goal.

To build Open Library, we need hundreds of millions of book records, a wiki interface, and lots of people who are willing to contribute their time and effort to building the site.

To date, we have gathered over 20 million records from a variety of large catalogs as well as single contributions, with more on the way.

Open Library is an open project: the software is open, the data is open, the documentation is open, and we welcome your contribution. Whether you fix a typo, add a book, or write a widget--it's all welcome. We have a small team of fantastic programmers who have accomplished a lot, but we can't do it alone!

Open Library is a project of the non-profit Internet Archive, and has been funded in part by a grant from the California State Library and the Kahle/Austin Foundation.