1) morgueFile
A free stock photo site that’s available to the public either for personal or commercial use.
2) Stock.Xchang
Stock.xchang is well organized and easy to navigate. And, there are plenty of pictures to choose from. There are different licenses for each photo.
3) Open Photo
An attractive looking stock photo community and resource. It has photos under several categories such as animals, computers, landscapes, still life and technology.
4) Our Media
OurMedia.org is a resource for media materials such as photos, audio and videos. Some photos are restricted and some are in public domain.
5) Google Images
It’s not always easy to tell which photos are okay to use and which ones are restricted.
6) Free Stock Photos
Some of its categories include: animals, scenery, sky, weather, wildflowers and plants. The photos are okay to use for both commercial and non-commercial use with attribution.
7) Image After
This collection of free stock photography can be used both in personal and commercial projects.
Flickr
Flickr is a photo storage service. Some users offer their photos for use to the public.
9) Buzznet
Buzznet is another photo storage service. Photos may have different types of restrictions.
10) PD Photo
PDPhoto.org is a collection of stock photography. Some photos are restricted and some are in public domain.
If you’ve yet to check it out you may have interest in Open Stock Photography. OSP is a new search engine that helps you find images from Wikimedia Commons. All of the over 980K images are available for any usage.
You might also want to check out Public Domain Images for hundreds of free images that you can use.