Flickermap
http://www.flickrmap.com/ 
Stocks photos from around the world which can be searched by countries.

morgueFile
http://www.morguefile.com/ 
Collection of high resolution digital images, which are free for public use.

NBII Digital Image Library
http://images.nbii.gov/
Collection of images related to nature and the environment. The library's collections include photographs of plant and animal species, scenic landscapes, wildlife management, and biological fieldwork. 

U.S. Government Photos and Multimedia
http://www.firstgov.gov/Topics/Graphics.shtml 
Collection of the government graphics, photos, and images; most may be used without permission or fee.

Image Searching tools

FaganFinder
http://www.faganfinder.com/img 
Searching several dozen sites that contain rich image repositories such as Flickr, Smugmug, and PhotoSite.

PicSearch
http://www.picsearch.com 
Picsearch image search technology has three main features. It has a relevancy unrivalled on the web due to its patent-pending indexing algorithms. Also, Picsearch has a family friendliness that allows children to surf in safety as all offensive material is filtered out by our advanced filtering systems. The site is also very user friendly as it's designed to be simple, fast and accurate.