Wikibooks is dedicated to developing and disseminating free, open content textbooks and other classroom texts. We currently host 5666 textbook modules, in various stages of development, from those needing a lot of work to those that are nearly perfect.
The books that did not fit the categories are all here. Also the books that fit in several categories (for example, Linux and C++) are here as well. Please send me a link in case something is missing.
provides free audiobooks from the public domain. Volunteers record chapters of books in the public domain and release the audio files back onto the net. The goal is to make all public domain books available as free audio books.
a Silicon Valley startup creating technology that makes it easy to share documents online. You can think of Scribd as a big online library where everyone can publish original content, including you! Publish Yourself Online