Project Gutenberg -- Over 30,000 books available for free. Has links to Gutenberg sites in other countries that also provide free online books
Global Text Project -- Free ebooks in six major subject categories.
HathiTrust Digital Library --HathiTrust is a partnership of major research institutions and libraries working to ensure that the cultural record is preserved and accessible long into the future. There are more than fifty partners in HathiTrust, and membership is open to institutions worldwide.
Digital Librarian: Electronic Texts, Primary Sources, Digital Libraries -- A large librarian-approved collection of links.
Humanities Text Initiative -- Links to full text resources in literature in English.
Internet Archive: Open Educational Resources -- Contains over 1,000 free university lectures, course materials, videos, and supplemental materials from universities in the U.S. and China.
The Literature Page -- Provides classic books, plays, stories, poems, essays, and speeches in the public domain online.
Textbook Revolution -- A student-run searchable collection of free electronic texts.
World Digital Library -- Digitized images of letters, maps, books, photographs, paintings, objects, and more from around the world, sponsored by the U.N. Education Agency.
These sites vary in content and quality, and I recommend carefully reviewing the terms, conditions and origins of the e-books on many of these sites. Be cautious about copyright, even with these resources. Any reproduction of these resources on a publicly-available web site may be a violation of copyright law.
Alex: Catalogue of Electronic Texts -- The Alex Catalogue of Electronic Texts is a full-text indexed collection of classic American and English literature as well as Western philosophy in the public domain and written or translated into English.
American Verse project -- A collaborative project between the University of Michigan Humanities Text Initiative and the University of Michigan Press. Presently contains 170 volumes of American poetry published prior to 1920.
ATHENA Authors and Texts -- Thousands of electronic texts, sorted by author's name.
Bartleby.com -- Thousands of free online classics of literature, non-fiction, and reference.
Bibliomania -- Includes links to online texts of both fiction and non-fiction books, plus study guides for some of them.
Bibliomania -- Free online literature and study guides. Bibliomania has more than 2000 free texts, study guides and reference resources.
Cambridge Digital Library -- Includes the digitized papers of Sir Isaac Newton, Christian works, Spanish chapbooks, Islamic, Sanskrit, Hebrew, and medieval Jewish manuscripts, and other treasures from the Cambridge University Library.
Classic Reader -- Read, search and annotate classic literature.
Complete Works of William Shakespeare --This site has offered Shakespeare's plays and poetry to the Internet community since 1993.
DailyScript --Contains the full-text of many classic and contemporary movie scripts as well as some TV scripts.
Digital Book Index -- Intended as a meta-index of major e-book sites. Provides links to more than 148,000 title records from approximately 1,800 commercial and non-commercial publishers, universities, and various private sites. Around 120,000 of these books and documents are available without cost.
Digital Culture Books -- Collection of ebooks that can be read for free online dealing with various aspects of digital culture.
E-books Directory -- E-Books Directory is a daily growing list of freely downloadable ebooks, documents and lecture notes found all over the internet. You can submit and promote your own ebooks, add comments on already posted books or just browse through the directory below and download anything you need.
eBooks: Free Books -- Contains links to sources of free online books from around the world in English and other languages.
ebooks @ Adelaide -- The University of Adelaide provides full-text ebooks of classic works of literature, philosophy, and history from a variety of countries, most available free online to anyone because the copyright has expired. Users can browse by subject, title, author or search by keywords.
eScholarship Editions -- Over 500 titles from academic presses available for free. Look for "public titles".
EServer.org -- The EServer is a digital humanities venture, based at Iowa State U, where hundreds of writers, editors and scholars gather to publish over 35,000 works free of charge.
Feedbooks -- “A universal e-reading platform compatible with all mobile devices where you can download thousands of free e-books, publish and share your own content, and create customized newspapers from RSS feeds and widgets."
Forgotten Books -- Provides online books, downloadable ebooks in PDF format, and inexpensive paperbacks; includes adult and children's titles in subjects such as classical fiction, philosophy, science, religion, folklore, mythology and sacred texts, in addition to secret and esoteric subjects, such as: occult, freemasonry, alchemy, hermetic and ancient knowledge.
Free Access Online Archives: -- A collection of links to free texts, papers, and journal articles online.
FreeBooks4Doctors -- FreeBooks4Doctors was created to promote the free availability of medical books on the Internet.
Free-eBooks.net -- Search by author or browse by subject category for free downloadable eBooks.
Free Resources for Educational Excellence -- Free animations, primary source documents, videos, and photos from various federal agencies.
Free Tech Books -- Free Online Computer Science and Programming Books, Textbooks, and Lecture Notes
Great Books and Classics -- Your gateway to the great classic books online
ManyBooks.net -- Provides over 29,000 free downloadable ebooks, searchable by author, title, and genre.
National Academies Press -- More than 4,000 books are available to read online for free. There may be a charge for downloading.
Native American Electronic Text Resources -- Links to the electronic texts of works by and about Native Americans, plus links to information on museums, artists, music, jobs, genealogy, gaming, movies, and more.
The Online Books Page -- Searchable links to over 35,000 books online in English and other languages, plus links to banned books online and prize winners online. From the University of Pennsylvania.
Online Library of Literature -- Links to online literature in English.
Online Texts -- Internet Public Library’s list of links to electronic texts.
Open Culture -- Free educational texts, courses, and media.
Open Library -- Contains over 1,000,000 free ebooks that you can borrow once you create an account. Allows only one reader per book at a time.
O'Reilly Open Books -- Specializes in books on computer programming and software.
Oxford Text Archive -- The aim of the Archive is to identify, collect, and preserve high-quality, well-documented electronic texts in a variety of languages.There are presently several thousand documents available.
Page by Page Books -- Includes hundreds of classic books online, including some children's books.
Project Gutenberg -- Searchable collection of online texts of books generally published before 1923 (classics).
RAND Corporation (RAND) offers more than 9,000 titles freely online as searchable, readable, and downloadable PDFs and adds more just-published and archival titles every week.
ReadPrint -- Includes free online essays, fiction, non-fiction, plays, poetry, and short stories from classic as well as popular 19th to early 20th-century authors.
Samizdat Press -- Free ebooks on math and the physical sciences.
2020ok: Directory of Free Online Books and Free Ebooks -- Contains links to free online books arranged by subject.
WESS' Collections of Western European Literature: Electronic Text Collections in Western European Literature -- Links to electronic literary texts in western European languages other than English.
Wright American Fiction 1851-1875 -- The purpose is to make available every novel published in the U.S from 1851-1875. Presently includes 2,887 volumes by 1,456 authors.