Open Clip Art Library
Open Clip Art Library (OCAL) is the largest collaborative community that creates, shares and remixes clipart. All clipart is released to the public domain and may be used in any project for free with no restrictions.
In the first instance there is Stock.XCHNG the leading FREE stock photo site. Huge gallery containing over 350,000 quality stock photos by more than 30,000 photographers.
Creative Commons Search
This search helps you find photos, music, text, and other works whose authors make their artwork available for re-use.
DotGovWatch Photo Search
Copyright FRee Image Library Search. Using a specialised Google search, from this page you can search thousands of images that are in the public domain as they have been released by the US Government.
Public Domain Clip Art
25,000+ clipart collection which is constantly growing.
A small but good quality of stock images, concentrating on nature mostly.
GIMP Archive: 32,000+ Royalty-free photos, organized by keyword.
Public Domain Depot
Not the biggest collection but when I am not finding what I am looking for elsewhere I will give this collection of Royalty Free, Copyright Free, Public Domain Images, Photos, Music and More. http://pddepot.com/
5000 Images mostly north america
Around 1000 images available
Good For backgrounds
Public Domain Pictures
Only about 500 Images but all from one artist, extremely high quality and absolutely no restrictions
Royalty Free STock Ohoto’s. Several thousand available variable quality
A massive clipart collection easy to search, navigate and use.
Large collection of mostly public domain photos. Read the license for each picture before use; also, model releases may not have been obtained for all photos.
Small but growing public domain stock photos released by a single photographer.