Public domain images - images that are freely available for any use - are numerous on the Web. Here are 12 high quality Web resources for public domain images that you can use for private or commercial purposes.
PDPhoto offers thousands of royalty free photos for your personal use (commercial use licenses vary by image).
If you need clipart for pretty much any project you can think of, you'll probably be able to find it at WPClipart, a repository of over 35,000 free, high-quality, public domain images.
Public Domain Pictures offers thousands of really gorgeous photos, images, and drawings, all available for your use online or offline.
Put together by the University of Wisconsin Eau Claire, this is a gigantic hub of links to copyright free and public domain image sources on the Web.
The Morgue File is a great source for public domain images you can use for private or commercial purposes; they tend to attract really high quality photo submissions.
Looking for some really unique images? Try Liam's Pictures from Old Books, a great source for over 2,600 high-resolution free images scanned in from a wide variety of old or out of print books.
Wikimedia Commons is a gigantic (over a million images at the time of this writing) repository of public domain images and other media content available in a wide variety of languages.
The New York Public Library has organized a huge collection of really wonderful public domain images, and made them all available to the public. This collection includes illuminated manuscripts, historical maps, vintage posters, rare prints, photographs and more.
Access hundreds of public photography images with Flickr Commons, a joint project with the Library of Congress.
From animals to travel and everything in between, Photos8 offers tons of great high quality images for personal or commercial use, including desktop wallpapers.
PicFindr is a search engine focused specifically on finding stock photos for personal or commercial use. You can filter your searches to look for different kinds of copyright licenses, as well as credit attribution.
Search for stock photos, Web photos, videos, and public domain images with Spffy, a search engine that looks for private and commercial use photos at a variety of prices (including free!). Licensing and attribution rights information are available on results pages, so you can figure out how you can use the photos or images you're looking at.