Internet Archive is a non-profit digital library offering free universal access to books. Internet Archive currently has over 6,000,000 fully accessible public domain eBooks.
Project Gutenberg offers over 54,000 free eBooks. It is one of the largest and most popular free books websites on the web allowing people to read books online for free.
Read any book is one of the best resources for reading books. you can Browse your favorite books and read them Online for free.
Open Library is also one of the best open, editable library catalog, building towards a web page for every book ever published.
Smashwords is a self-serve publishing service. IT allows Authors and independent publishers to upload their ebooks.