Stock

Comstock Images
Business, Arts and Entertainment, Photography, Stock - Comstock Images. Searchable database of rights-protected and royalty-free images.
https://comstock.com/
Robert Harding Picture Library
Business, Arts and Entertainment, Photography, Stock - Robert Harding Picture Library. Offering an image collection of travel, geography, culture, and the natural world.
https://www.robertharding.com/
ImageDJ.com
Business, Arts and Entertainment, Photography, Stock - ImageDJ.com. Variety of photos available on CD or for single image download.
https://www.imagedj.com/
The Royalty-Free Stock Images Directory
Business, Arts and Entertainment, Photography, Stock - Royalty-Free-Stock-Images. Sites providing free photos, commercial photos, illustrations and footage, all royalty-free.
http://royalty-free-stock-images.com
Intuitivmedia
Business, Arts and Entertainment, Photography, Stock - Intuitivmedia. Images free for non-commercial use, can also be purchased and downloaded.
https://im-visions.com/
Stock Photos
Business, Arts and Entertainment, Photography, Stock - ShutterStock. Royalty-free photography for web or print, subscription model.
http://shutterstock.com
Science Photo Library
Science Photo Library Website - The World's Leading Provider of Science Photos
http://sciencephoto.com/
Mira
Business, Arts and Entertainment, Photography, Stock - Mira. Presenting the work of professional photographers members of Creative Eye, an artists' cooperative.
http://mira.com/