Open Library

http://openlibrary.org/ One web page for every book ever published. It's a lofty but achievable goal.

To date, Open Library 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 are open, the documentation is open, and we welcome your contribution.

Reference:
About Us (Open Library). (n.d.). Welcome to Open Library (Open Library). Retrieved September 25, 2011, from http://openlibrary.org/about