I think this list of math and science Enrichment Opportunities at the MIT admissions site
http://mitadmissions.org/apply/prepare/enrichment is interesting, as is the list of summer program for high school students mentioned by Caltech
http://admissions.caltech.edu/parents#summer"Summer programs that many of our admitted students have attended include:
Lead Engineering
Summer Science Program (SSP)
Research Science Institute (RSI)
Minority Introduction to Engineering Entrepreneurship and Science (MITES)
Women's Technology Program (WTP)
The Ross Program
COSMOS (California State Summer School for Mathematics and Science)
Program in Mathematics for Young Scientists (PROMYS)
Honors Summer Math Camp (Texas State University, San Marcos)
Canada/USA Math Camp
NanoBusiness Talent Program
The Science Training Program Directory"
To be admitted to these summer programs, participate in the math and science olympiads mentioned by MIT, or to do science research, a student may need to accelerate in science, going faster than the typical
9th grade biology
10th grade chemistry
11th grade physics
12th grade AP biology, chemistry, or physics
sequence for good college-bound students. Elizabeth Wissner-Gross's book "What High Schools Don't Tell You" discusses math and science "tracks" for students aspiring to attend selective colleges.
The MIT site has other informative pages, which mention curricula such as EPGY and AoPS used by many Davidson forum members.
