I just found out about Flikr, which is hosted by Yahoo. You become a member and then you are able to use any pictures or videos you can find from other people as long as there isn't a copyright listed in the right-hand column and you credit them on your page. It's also really great because you let the person know you used their photo or video and then post a link to the page you put the photo on in the comments section after the photo you used. To see an example you can go to this page from my site
http://www.child-behavior-guide.com/...-behavior.html
Scroll down to the boy with glasses and you will see how I credited the photographer. Then if you click on the picture you can go to his page, scroll down the comments and see how I let him know it was on my site. A lot of pictures on Flickr look really professional, allow you to get some extra traffic and provide the photographer with some acknowledgement as well. A win-win for everyone! If you look down further from my comment, he also thanked me for letting him know. To learn how to post the link in the comments section read the "How do I format my comment?" right underneath the comment box.
You can also get videos from YouTube, which if they have the Embed codes on the right side of the video available you can cut and paste them to be put onto your site.