Clip art, photos and images free for Educational (non commercial) use donated by the Naace Community through NaaceTalk.
Dorling & Kindersley Range of high quality digital photos covering a number of curriculum topics
Northumberland Grid clipart linked to topics in the curriculum
2Simple clipart linked to topics in the curriculum (Nigel Canin has confirmed the clipart is free for educational use)
Clip Art linked to US school topics
Photographs covering a range of topics
Images from East Riding RBC
Images linked to US education
A picture search engine which shows the range of pictures to match your search and links to the source. (n.b. Users would need to check the copyright against each sourced picture).