I have been concentrating on my son’s middle school math last two years.
It is pretty fruitful:
My son took January 28, 2012 SAT I . He was 8 year 11 month old. He scored 700 on math section.
( http://cty.jhu.edu/set/index.html )
He took AMC 8 on November 23, 2012 and scored 23 out of 25. The top score in Luther Jackson Middle school and Frost Middle School (all are 8th graders) is also 23.
He was 9 year 9 month old. AMC 8 score of 23 put him in the top 1% of AMC 8 nation-wide and in distinguish honor roll.
On Feb. 5th 2013, he took AMC 10A. He scored 111. The cutoff of top 2.5% is 108.0. This cutoff score of 108.0 is also the AIME qualification line.
So he qualified for AIME when he was 10 year 0.1 month old.

During the process of helping my son with his math, I have gone through all the middle school and high school math.
I finally finished the long expected:
Advanced SCAT Math Question Book .
It is my 1.5 year of hard work. I am very happy it is available now.