Mary Beth,
Your son sounds so much like mine - although my son is now 8. By the time he started Kindergarten,he had read the 1st 3 Harry Potter Books and had mastered multipication and division and had moved on to mixed fractions. He was self-taught, I provided him workbooks and he did all the work.
Some of the things that helped us were - a second language (we paid for a private tutor) and piano lessons (which he excels in). These were 2 things that he didn't know and challenged him to a degree. We also live close to CMU and he participates in their C-Mites program for Gifted Children ( he loves this b/c he is with kids like him). We are also doing Distance Education through Johns Hopkins CTY program.
In school, he is Math Accelerated and works on special projects with his Gifted Resource teacher. We have a pull-out program for Gifted(not my favorite choice_) but he is with the resource teacher 3-4 times/week. Because he isn't challenged to his potential at school, we use outside resources to challenge him. He is very well liked by his peers (something we were concerned about, since he tends to speak well beyond his years)and has made great social strides since Kindergarten. You sound like you are doing all the right things as a parent.
It is very challenging having a Gifted child, but so rewarding at the same time. The Hoagie's Gifted Education website was a great resource to me as well. Good luck - any question feel free to contact me. Thanks
