Free Stock Photos
We have listed several sources for stock photos below. Many of these have both paid photos and free photos. Most of the Free Stock Photos are bound by certain licensing requirements. You may be able to use the photos for instance in a non commercial way, but not for commercial gain.
Picsearch.com is a good option for the times that you are not really sure what kind of photo you are looking for. This wide array of stock photos has various licensing restrictions which you can check out for each photo.
MorgueFile.com offers stock photographs in high resolution digital. I have found this site to be very user friendly when looking for stock photos which are not bound by too many restrictions.
SXC.hu has some of the highest quality images available from both professional and amateur photographers. The individual photographers do set the terms for usage of each photo, but you can easily find photos suitable for almost any project.
FreeMediaGoo.com has a large selection of images to choose from. Most of these images may be used without too many restrictions, but always check the conditions of use.