Here are links to free-use images:

Wikimedia Commons

The Open Photo Project


AnimHut 180+ free to use image websites

Flickr click on selected image, scroll down and select 'creative commons'

Flickr Creative Commons

Flickr-Storm

Wikipedia Public domain images

GovWatch copyright-free images under categories such as Dept. of Defence; Antarctica, NASA, etc.

Old Book Illustrations under categories such as animals, landscape, scenes, buildings/monuments, science/technology, etc.

Unprofound.com You can search image according to colour; free to use in any personal or commercial project (check)

Open photo a wiki-based photography site; browse or search by tags

Image After free images and textures under categories such as elements; fabrics; wood; fur; goo; nature; rock; roof, etc.

Blogging Sueblimely Sue Bride's blog with many links to free image sites

Vintage Pixels a large database of historical, high quality, free-for-use images which allows people to share their archived photos

Compfight If you click on: Tags you will have the option of searching through all the tags or all text; Creative Commons is a link to go between all, off or commercial searches; Seek Original allows you to choose whether or not you want original images.