Public Domain Clip Art and Photos

I'll add more or add your own in comments.

http://www.pdclipart.org

http://www.pdphoto.org/
http://www.publicdomainpictures.net

The Free Site - freebies to put on your websites

This is an older directory of webmaster / software tools, i.e before web 2.0 took off, that still has some handy links if you are looking for webmaster freebies, sticky content, free images etc.