A plethora of sites provides assistance in finding images
on the web. For example, google now
offers an image search. However beware: not all images which appear on google image searches
have been placed on the web legally and, even if legally on the web, they are not necessarily
available for you to use as you please. Be sure to read the terms of use on the site where an
image is located before proceeding to use the image.
Having said that, many images on the web are available
for use. See the list of sources below, and
also visit the Technical Advisory Service for Images (TASI) website at www.tasi.ac.uk, particularly
the page on finding
art images. 
