I just stumbled on http://www.morguefile.com/ who apparently host 25000 images that are free for use. Consulting their FAQ:
*1.* Are the images really free? Yes, all images are really free and they can be used in your commercial projects without permission or credit from the photogrpaher. Although selling prints, selling the images directly or claiming the photo is yours is prohibited. *Note:* You are responsible for the content of the photos you use. It is very much the same as if you had taken the photograph yourself, you must still obtain proper permission for property or people depicted in the photos if any.
*2.* Why? This web site follows in the tradition of the world wide web. It is dedicated in the proposition of free thought and exchange.
All that seems to be quite compatible with our line of efforts. Maybe we can even convince them to license the images under GFDL; someone "official" (foundation) should write a mail. At the very least, we can use them in the wikipedia, as we do not intend to sell prints or files "as such", but within an encyclopedia at most. A note to cite the source, and not to sell these images as high-quality prints or files should suffice; all other use is allowed.
The animal photos alone appear to be a gold mine for us.
Magnus