Jurriaan-
Is there any reason why one couldn't use pictures from http://www.sxc.hu/ for wikipedia?
Nice find! Using these photos should be no problem if there are no individual usage restrictions on the photo in question. The only problematic part of their Terms of Use which I can see is the following:
--- 3.) You are not allowed to use any of the images found herein for the purpose of spreading hate or discrimination, or to defame or victimise other people, sociteties, cultures.
from http://www.sxc.hu/info.phtml?f=terms ---
However, this is from the Terms of Use of the website itself, and not a required condition for uploaders, but for downloaders. So I doubt it has any real legal effect.
Regards,
Erik