e-Books 

Digital Book Index provides links to more than 165,000 full-text digital books from more than 1800 commercial and non-commercial publishers, universities, and various private sites. More than 140,000 of these books, texts, and documents are available free. 

Project Gutenberg - The place where you can FREELY download over 33,000 ebooks to read on your PC, iPad, Kindle or other portable device.
Bookyards has thousands of books in its collection and thousands more web links to other freely accessible online libraries.

The Online Books Page. Their catalog  are licensed for others to use under a Creative Commons Attribution-ShareAlike license. 

Alex Catalogue of Electronic Texts 

This is a collection of full texts on topics around American literature, English literature, and Western philosophy. 

Bartleby.com: Great books Online Many classic texts and references are available in this award-winning website free of charge. 

The Online Medieval & Classical Library - The OMACL is a collection of some of the most important literary works of Classical and Medieval civilization. 

e-Books Directory. Free contemporary novels of various genres like romance, adventure, sci-fi, biography, etc.