Here are a few links to web pages that offer public domain and royalty free works, I have categorized a large number of public domain and royalty free resources under the industry resources tab and then as sub-menu tabs specific to each industry, you’re more likely to find what you are looking for there.
- Wikimedia Commons – tons of free stuff here
- Creative Commons – lots of resources
- Internet Archive – video, sound, pictures
- The National Archives – free government publications
- PD info – Public Domain Music and Royalty Free Music
- Project Gutenberg – free ebooks