The Internet Archive is a 501(c)(3) non-profit that was founded to build an Internet library. Its purposes include offering permanent access for researchers, historians, scholars, people with disabilities, and the general public to historical collections that exist in digital format.
The Internet Archive makes for a one-stop shopping experience in that it contains materials from such diverse collections as The LibriVox Free Audiobook Collection, The Library of Congress, The Prelinger Archives (thousands of documentary and other films), and the Grateful Dead!
Enjoy this little film from the Prelinger Archives:
The Open Library part of the Archives gives you full access to the text of thousands of out of print books, which is especially helpful to those doing history and social history projects. Also, some of these books are made available as ebooks. This is great for those readers who are revisiting the classics. Readers can find, for example, one of Jane Austen's lesser known novels, Mansfield Park, in 8 ebooks!