- Google Books
Google has partnered with over 20,000 publishers and authors, and several major research libraries, to makes their books discoverable through Google Books. While only limited text can be viewed from books still under copyright, the full text of many public domain books, especially those published before 1923, is available. Use the Advanced Search page to limit your search to full-text or public domain books.
- HathiTrust Digital Library
Through a partnership with more than two dozen research libraries, HathiTrust currently makes available more than 4.9 million digitized volumes, approximately 15 percent of which are in the public domain. The HathiTrust Digital Library complements content available through Google Books: while some content between the two services overlaps, HathiTrust provides some content Google does not, including digital collections unique to participating institutions, works from institutional repositories, and native born-digital materials.
- Internet Archive: eBook and Texts Archive
The Internet Archive includes the full text of more than 2.5 million online books and texts, including works of fiction, popular books, children's books, historical texts, and academic books. Books can be dowloaded and read in a variety of formats, including text (.txt), PDF, ePub, Mobi (for Amazon.com's Kindle), DAISY, and DJVU.
- The Online Books Page: Archives and Indexes
A large compilation of full-text literature resources on the Web. Includes sections on general-purpose collections with substantial English-language listings (large-scale repositories; significant indexes and search aids; and significant smaller-scale archives), foreign language and literature resources, and specialty archives.
Information from the Library of Congress: http://www.loc.gov/rr/askalib/faq.html#aalfaq5