Here is the best FREE stock photo site I have found. Read the fine print, all the work can be used for your own use, but to use it commercially contact the artist for permission!
This is a really good article explaining copyright and open source code. It explains what your ownership is in open source and how it fits into copyright. The section "ownership of copyright in software" outlines Work for Hire opposed to Sole Developer right when creating open source material.
Great documentary focusing on the artist GirlTalk and the popular mash-up "bootleg" music style.