Public domain media

There is quite a bit of cool public domain material around, I thought I'd start a bit of a list.

Internet Archive
A huge range of resources here. Can be a bit of a challenge to wade through, but has media of every type, and playing around with the advanced search can reveal some gems.
Project Gutenberg
Project aiming to make free ebooks available for works that have expired copyright or are public domain. Some of the ebooks have different usage rules.