How to find stock photography...
You can find images to use in your layouts or buy an image for commercial use.

http://www.indexstock.com/

http://www.photodisc.com

http://www.corbisimages.com/

http://www.stockmarketphoto.com/

http://creative.gettyimages.com/imagebank/

http://www.weststock.com/

http://www.mediafocus.com/

http://www.tssphoto.com/vt.html

http://www.accessstock.com/

http://www.photographiclibraries.com/

The Library of Congress. This has much more than photos but the photos are wonderful.
http://www.loc.gov/ 

For your information, here are the copyright laws...
http://lcweb.loc.gov/copyright/circs/circ1.html

http://www.benedict.com/

Royalty Free Content / Images:
http://www.freesticky.com/stickyweb