Did you know that it is illegal to use most of the pictures in Google Images without direct permission? Well it is. Here is a tutorial on finding legal image sources on the web. Below, you will find other sites you can use with a clear conscience. You still have to cite them on your Reference list, though!
"Clip art licensed from the Clip Art Gallery on DiscoverySchool.com" at http://school.discoveryeducation.com/clipart/
Search millions of photographs from the LIFE photo archive, stretching from the 1750s to today. Most were never published and are now available for the first time through the joint work of LIFE and Google.
Creative Commons will help you find photos, music, text, books, educational material that are free to share or build upon.
Pics4Learning is a copyright-friendly image library for teachers and students. The Pics4Learning collection consists of thousands of images that have been donated by students, teachers, and amateur photographers.
EBSCOhost Images - Their images may be printed for personal, non-commercial use; used in presentations for educational use; but may not be posted on the Web or used in any other form of mass media without express written permission from the copyright holder.
The Stock Exchange Whether you just want to browse their huge image gallery or want to share your own photos with others, this is the site for you! The gallery contains over 350.000 quality stock photos by more than 30.000 photographers!
Discover Education's Clip Art GalleryAdd graphics to your next project, whether it’s for home or school. Choose from hundreds of original clip art pieces, including animations! Credit must read - "Clip art licensed from the Clip Art Gallery on DiscoverySchool.com" and include a link to the Discoveryschool.com Web site.
If this isn't enough, you’ll find 40+ Best Sources To Download High-Quality Royalty Free Stock Images and Photographs over web. You can use these images in your projects without paying single penny. However, just make sure to read the license agreements carefully as they can change from time to time.