http://www.1stopstock.com/index.html
Contains links to several sources of digital photos, etc.

http://www.weststock.com
Weststock - Simple but effecient site

http://www.photodisc.com/
Photodisc - Shop for royalty-free photos

http://www.digitalimageonline.com/
Digital Image

http://www.pictor.com/
Pictor

http://www.estock.com/
e-Stock

http://www.imagebank.com/
Image Bank

http://www.corbis.com/
Corbis - a little art-sy but high quality photos

http://www.webshots.com/
In addition to photos, you can download screensavers and backgrounds

https://pvind.photonet.com/account.htm
http://www.ezprints.com/
Kodak's PhotoNet and ez prints provide web-based digital photo services

http://www.clubphoto.com/
http://www.webphotos.com/
Customizable photo albums