If you don't see your intended subject listed, try the search form. Excalibur provides images in small thumbnail versions, six to a page. WebSEEK presents images in thumbnail format, fifteen to a page. WebSEEk also features a postcard sender, which dispatches an email message containing the URL of an image and a message. To find images with more of an academic angle, try the Amazing Picture Machine.
Results appear as text-only listings with links to actual image files.
If you're interested in art in particular, try the Fine Art Museums of San Francisco ImageBase. The ImageBase contains over 60,000 images of paintings, photographs, sculpture, and other artwork. You can browse particular exhibitions or search for artwork by artist's last name or keyword. One potential pitfall when searching for images is the variety of the results, depending on the keywords you supply. On the other hand, viewing the Hawk category brought up page after page of hawk photographs.