Below you will find a listing of royalty-free sites that specialize in images, sounds, and video. Royalty-free basically means that you do not need to pay any fees to use something in your own work. However, royalty-free does not necessarily mean that you can use items without giving credit to their original creator! Some of the content below might be under a Creative Commons license. If you make use of someone else's content, be sure to honor the wishes of the creators.
Ball State's Copyright & Intellectual Property Office has compiled a nice list of free Internet resources.