These are Web sites offering electronic versions of books for free. The majority of the books are older ones due to their copyrights expiring.
Alex Catalogue of Electronic Texts - This is a large collection of American and English works of literature and philosophy. Examples include works by Charles Dickens, Martin Luther King Jr., Plato, William Shakespeare, Adam Smith, Bram Stoker, Mark Twain, Voltaire, and many more. Books are available as txt or pdf.
Baen Books - A number of books from this science fiction and fantasy publisher are free. New titles added every month.
Bartleby.com - This is another huge collection of resources. Includes works of fiction, non-fiction, reference, and poetry. Examples include the Columbia Encyclopedia, Bartlett's Quotations, Roget's Thesaurus, works by Jane Austen, Victor Hugo, Homer, Carl Sandburg, Emily Dickinson, Albert Einstein, and on and on. Book format is html.
Books Should Be Free - Free audio books in mp3, iPod, or iTunes formats.
Bookyards - A web library that provides of a wide variety of ebooks.
Children's Books Online: The Rosetta Project - Provides hundreds of children's books from the 19th and early 20th centuries. Books may be read online or downloaded, and consist of scanned images of pictures and text. Includes books in other languages.
UC Press E-Books Collection, 1982-2004 - This collection includes almost 2,000 books from academic presses on a range of topics, including art, science, history, music, religion, and fiction. Access to the entire collection of electronic books is open to all University of California faculty, staff, and students, while more than 500 of the titles are available to the public.
InkMesh - A search engine for free e-books from more than thirty different sources. Also compares prices of e-books for various e-readers. Search by either title or author.
International Children's Digital Library - Location for many children's books from around the world and in various languages. Books consist of scanned images of the original. Great subject browsing.
LibriVox - Free audio books in multiple formats, including mp3.
Manybooks - This site carries a wide variety of eBooks.
Online Books Page, University of Pennsylvania - Archives over 800,000 books and includes special features such as Banned Books, Prize Winners, and Women Writers.
Open Library - This site includes access to over one million books. It is an open, editable library catalog, building towards a web page for every book ever published.
Pinterest Boards for E-books - 10 boards for e-book fans
Project Gutenberg - The granddaddy of archived books. Fiction, non-fiction, reference works, musical scores, and much more. The books come in a variety of formats, including plain text, html, and audio.
Wattpad - This site includes stories from both published and unpublished authors. It is a network of user-generated content, like YouTube, but for stories. There are millions of stories on it that are free and downloadable to computers or mobile devices.