InterArtCenter

http://interartcenter.net/

InterArtCenter is an online resource dedicated to stock photography where you can browse and download royalty free stock photos, 3D cliparts, 3D models, 3D wallpapers and also Flash animations available for both personal and commercial use.

No registration is needed to download the free images. Photos are available in high-resolution and multiple sizes. Photographers are also welcome to contribute and sell their own photos through InterArtCenter to monetize their image inventory.

Public-Domain-Photos

http://www.public-domain-photos.com/

Public-Domain-Photos is a stock photography site where you can find a large number of royalty free stock photos and cliparts released under the public domain. All images on the site can be used for both personal and commercial use.

You can download all images on Public-Domain-Photos without even registering. Photos are available in high-resolution and only in one size. Attribution is not requested but it is advisable if you want to help the site grow and provide even more free images.

Toasto

http://www.toasto.com/

Toasto is a stock photography site where you can find both free images for personal use and royalty free stock photos for commercial use. All images on the site require attribution and free images cannot be modified in any way before sharing.

All images are available in one, high-quality size and are available for download right away, without registration needed. The site has also a nice collection of desktop wallpapers and iPhone wallpapers that you can download for free.

Public Domain Photos

http://public-photo.net/

Corbis Images is a stock photography site where you can browse and download an increasing number of royalty free stock photos available for personal and commercial use. Registration is not required to download any of the free images on the site.

Photos are available in one, high-quality size and every image carries technical details of the camera which took the picture. There are several categories to choose from like Animals, Funny, Signs, Technology, Birds, Clothing, Food and Drink, etc. To download an image, hover on it with your mouse pointer, right-click and select "Save Image As...".

Corbis Images

http://www.corbisimages.com/

Corbis Images, one of the leading stock photography sites on the market, has a whole area dedicated exclusively to royalty free stock photos that you can download to enrich both your personal and commercial design projects. Registration is compulsory to purchase the images.

You can either buy single images or whole collections of images which belong to several categories like sports, nature, Industry and more. All royalty free images are in high-quality and available in different sizes. The lightbox feature lets you conveniently bokmark images as you browse the archive for later purchase or to checkout all your stock photos in one shot.