Library of Congress Online includes over 60 classic books that can be accessed and read online.  

American Literature contains over 400 classic books.  These include titles such as Dracula, Alice in Wonderland, Don Quixote and much more.  

Project Gutenberg is a library of over 60,000 free eBooks.  Their mission is to digitize and archive cultural works.

Project Gutenberg en español: this link will take you the Spanish language books in the Project Gutenberg website.  Currently, there are over 600 titles.

Loyal Books has over 7000 audiobooks and ebook downloads.  

Loyal Books en español: this link will take you to the Spanish language books available through Loyal Books.