archives.org - a digital library of Internet sites and other cultural artifacts in digital form
Bartleby.com: Great Books Online - Quotes, Poems, Novels, Classics and hundreds more
ChestofBooks.com - Read Books Online for Free
Collections - HathiTrust Digital Library
Internet Archive - non-profit library of millions of free books, movies, software, music, websites, and more.
JSTOR - more than a thousand academic journals and over 1 million images, letters, and other primary sources, JSTOR is one of the world's most trusted sources for academic content.
LibriVox - provides free audiobooks from the public domain.
National Science Digital Library - Serving science, technology, engineering, and mathematics education
Open Access - Cambridge Core