In the archive are 71,000+ books from the Cornell University Library. As the site says:
These books, the originals of which are in the Cornell University Library, were digitized in 2008 with funding by Microsoft Corporation. Scanning was performed by Kirtas Technologies; OCR was performed by, and derivative formats created by, the Internet Archive.
There are no known copyright restrictions in the United States on the use of the texts. More information on rights issues associated with public domain texts can be found at http://cdl.library.cornell.edu/guidelines.html.Nice to know that this cancelled project from Microsoft did create a lasting, positive legacy.
The books are available in a variety of file formats including PDF, EPUB, Kindle, Daisy, JiVU and others.