1.http://books.google.com 

Google has a online books service called Google books.Some of the books give you a couple of chapters however most of the books are complete versions.

2.http://www.gutenberg.org 

The Gutenberg Project, There are tens of thousands of books available on this fine site, and they are all yours free for the taking and reading.

3.http://www.dailylit.com

There are more than 800+ online books for free.Choose your favorite books,select what time you want to receive messages,so submit your email address and Subscribe it.