DS also tries to play math games and help his friends with math problems. He's darlingly sweet about it, but again, I try to lead them to something non-academic. I want him to connect with his age-peers, and I don't think sharing academic interests when he's so far above their level is not going to foster those relationships.
These are my concerns for my DD, however, I also see our homeschooling experience as a great opportunity for my DDs friend. She attends the only public school in our community and IMO it is pretty backwards. They are not at all interested in accommodating bright kids, this is how we ended up homeschooling DD. Because of this I do not want to let go of academics completely. I just want to find a way to make this work so that everyone's self esteem remains intact. I really want her friend to have a chance to learn stuff that I know she is not being exposed to at school. She's a great kid and it's hard to watch children go through school without sufficient challenges, even when they aren't your own

Thanks for your replies. You've given me some good ideas.