There are 19,000 free ebooks in the Project Gutenberg Online Book Catalogue.

http://www.gutenberg.org/

http://www.truly-free.org/

http://www.bibliomania.com/

http://www.readprint.com/

http://www.readbookonline.net/

http://www.fictionpress.com/

http://etext.lib.virginia.edu/

http://www.free-ebooks.net/

http://manybooks.net/

http://www.worldwideschool.org/library/catalogs/bysubject-top.html

http://www.thefreelibrary.com/

http://www.baen.com/library/

http://www.ebooks3.com/

http://www.bookyards.com/

http://www.free-online-novels.com/

http://www.starry.com/novel/authors.htm

http://www.bygosh.com/thebestnovels.htm

http://www.bookspot.com/ask/

http://www.online-literature.com/

http://onlinebooks.library.upenn.edu/

http://www.infomotions.com/alex/

http://www.pagebypagebooks.com/

http://www.literature.org/
References :