The Child and Adolescent Bipolar Foundation saved my sanity when our older daughter was diagnosed bipolar at the age of four:
Child and Adolescent Bipolar Foundation: Vital information on bipolar disorder in children, teens, and young adults.
The biggest thing I learned: get the right meds and question authority. Our daughter has been stable and happy on Lithium and Abilify for a couple of years now, but she wouldn't be on either of those if I hadn't educated myself and found the right doctors.
Audrey