Yotophoto is a specialist image search engine with an index of more than a quarter of a million Creative Commons, Public Domain, GNU FDL and other copyleft images from places like Flickr, Morguefile, sxc.hu etc. Great resource if you’re looking for a meta search facility for pictures. [Thanks Tom]
Yotophoto is a search engine for free-to-use stock photographs and images. These are images that are either in the Public Domain or released under generous Creative Commons, GNU FDL or similar licenses…Our goal is to help people locate, remix and republish open and copyleft images. We aren’t just about ‘free stock photos’ for designers, but also about helping educators, bloggers and digital artists find photos they can use without fear of “the man”.
Yotophoto is a great resource and they have an advanced search where you can filter images by resolution (image size), license type and even colour, to find just the right photo. PicFindr is another resource similar to yotophoto but with a different search approach; PicFindr literally performs your search on several sites simultaneously (including those listed above) and compiles the results into a single page with links to the individual photos, their terms of use and a link to the search results at the host site. Yotophoto is currently ahead in terms of advanced search options, but PicFindr is up and coming. For full disclosure, I am the developer of PicFindr.
Looks like the Yotophoto website doesn't work now :(
I want offer my free photos stock collection at http://www.download-free-photos.com/
Enjoy,
Alex