Over 20 million books already have a page on OpenLibrary.org, and over 1 million of those give you access to a full-text, downloadable version.

It is an Open project - the software is open, the data is open, the documentation is open, and the site is open. Anyone can participate in this project, whether you're a librarian who wants to add records of digitized books to her local catalog, or you're a lover of books who wants to make sure his favorites are well represented, or you just want to find a good book to read for free, or you're a programmer who wants to build something new on top of this data.