ELTpics - Copyright free images for education

A collection of over 3000 images sorted by category for use in class, or as resources. Images can be downloaded, in different sizes, by clicking on the ‘Actions’ button on each individual image’s page.

All the images are licensed as Creative Commons, which means that as long as you attribute the source and do not use them for commercial purposes there are no copyright restrictions (more details here http://creativecommons.org/licenses/by-nc/2.0/ ).

They have been put together by teachers around the world; if you want to contribute, this page explains how:
http://sandymillin.wordpress.com/2011/05/18/how-to-join-in-with-eltpics/