Not only with children, but with disabled (many deaf)(also for the mentally ill) people, senior citizens and a wonderful programs where prisoners train puppies to be service dogs for the disabled. Many soldiers coming home from the Middle East with major adjustment problems have dogs to help them.
Since you asked for organizations specifically that work with children:
1. Interactive Computer Program: www.animalagentz.com
2. The relatively new organization AAT (Animal-assisted Therapy)has encouraged groups, such as:
3. The National Capital Therapy Dogs, Inc. atr the National Institute of Health (NIH)
4. The Delta Society (which I support, specializes in AAT
5. Pet Partners - also using AAT
6. The Federal Emergency Management Agency (FEMA) in disasters
7. Assistance Dogs International
Sra