Open Educational Resources

Hippocampus offers educators a wide variety of multimedia content online, including videos, animations, and simulations. In addition, it offers educators the ability to create playlists for their students, which correlate specifically to their particular instruction material.
Site-specific License.

The Open Course Library (OCL) is a collection of shareable course materials, including syllabi, course activities, readings, and assessments designed by teams of college faculty, instructional designer, librarians, and other experts.
CC BY 3.0

Project Gutenberg offers over 50,000 free eBooks; download them or read them online. Offers high quality eBooks; includes eBooks that were previously published by bona fide publishers.
Most titles are in the public domain, but includes some copyrighted titles, for which permission for unlimited non-commercial worldwide use has been given.