Hi Grinity,
Thanks for all the information! I will check out the books you suggested. It's so great that I found this forum. It's hard to raise these questions at school without sounding snobby.

I don't think our school has a gifted program anymore because of budget cut.
My son has always been an advanced reader and he reads all sorts of books. He doesn't mind reading science books, like books about atom, elements, etc . And he learned a lot from all these readings. I hadn't thought about skipping grade, or going to another program until now.
Starting this year, he started to complain about how boring the math and science classes were. He is very interested in math and science. But the school only teaches things that he already knows. Yet, he still has to do homework on it. (Probably the main reason he dislikes the classes ) :p
Did your kid's teacher approach you about your kid's talent? I've heard stories about teachers sending the students to take IQ test, etc. On one hand, I don't want to be a mom who "thinks" her kid is gifted. On the other hand, I want to provide him with the best options available for him.
Homeschooling? Not sure I have the discipline to do it.
Thanks again!