Internet Archive: marvelous resource

The Internet Archive is a non-profit digital library with the stated mission: "universal access to all knowledge."^[2][3] It offers permanent storage and access to collections of digitized materials, including websites, music, moving images, and books. The Internet Archive was founded by Brewster Kahle in 1996.

http://en.wikipedia.org/wiki/Internet_Archive

Open Library

Main article: Open Library

The Open Library is another project of the Internet Archive. The site seeks to include a web page database for every book ever published, a sort of open source version of WorldCat. It holds 23 million catalog records of books, in addition to the full texts of about 1,600,000 public domain books, which are fully readable and downloadable.^[8][9] Open Library is a free/open source software project, with its source code freely available on the Open Library site.

http://www.archive.org/