Useful Links for finding Photos

Google images - go to Advanced Search ... choose "free to use, share" or "free to use, share or modify".
Flickr - choose "Commons" from the drop-down menu or go to advanced settings and check the box for "Creative Commons".
morgueFile - photo collecting containing thousands of free images anyone can use for free.
Wikimedia Commons
http://www.sxc.hu/
http://photorack.net/
http://backgrounds.mysitemyway.com/ - great webpage backgrounds