Find creative commons images with behold.cc/
This site searches CC Flicker images you can use in your practice, this site specialises in finding creative commons images, have a go and please let us know what you think and how you used it, is it just same as searching in Flicker direct or does it save time by cutting out the Flicker interface? http://www.behold.cc/
Also see http://s1.imagestamper.com/login.jsp ImageStamper is a free tool for keeping dated, independently verified copies of license conditions associated with creative commons images. You can use it to safeguard your use of free images from license changes, or to prove you are the original image creator.