Public Domain Materials

What is public domain?

Basically a license to steal. You can use any public domain material for any use you want,
even to sell, without getting permission from anyone.
There are no copyright issues for public domain, as the majority of the people who made
the material are deceased.

Sites to get public domain real books (useful for photocopying)

www.abe.com
www.alibris.com
www.addall.com/used

(see public domain laws at site below before purchasing an out of print book)
http://www.copyright.cornell.edu/public_domain/

Public Domain Ebook Sites
www.gutenberg.org
http://zuhause.org/dp/gfound.html
http://manybooks.net/
http://www.archive.org/details/texts

Public Domain Audios
LibriVox
Internet Archive: Audio Books & Poetry
Maria Lectrix
http://www.partnersinrhyme.com/pir/free_music_loops.shtml

Public Domain Clipart
http://openclipart.org/

I hope this helps. Remember to check each work before you use it.