Non-profit organization that works with the U.S. Customs Service and the FBI in enforcing anti-child pornography laws. Includes their goals, FAQ, press releases, details of members, and a facility to report suspected sites... 

http://www.asacp.org/

Provides contact details of field offices of the FBI in major cities throughout the United States and San Juan, Puerto Rico... 

http://www.fbi.gov/contact/fo/fo.htm

IWF is an organization working with the internet industry, police and Government. If you come across child abuse images hosted anywhere in the world, you may report them here... 

http://www.iwf.org.uk/

Dedicated to identify technological or other methods that could help reduce access by minors to harmful material on the internet... 

http://www.copacommission.org/