Marin Math Circle
Harvard Math Circle
San Jose Math Circle
Salt Lake City Math Circle
South Alabama Math Circle
Stanford Math Circle
San Francisco Math Circle
Metroplex Math Circle
UC Davis Math Circle
MCCME
Oakland/East Bay Math Circle
Mobile Math Circle
Circle for Teachers
Long Beach Math Circle
Los Angeles Math Circle
Orange County Math Circle
San Diego Math Circle
Colorado Math Circle
DC Math Circle
Florida Math Circle
Miami Math Circle
Riverbend Math Circle
The Math Circle in Boston
Global Math Circle, Ontario, Canada

SPARC 2013
Firecracker Math Summer Camp 2013
A* Summer Math Camp (UC Santa Clara)
A* Summer Computer Science Camp (Bay Area)
Hampshire College Summer Studies in Mathematics (Amherst, MA)

Elementary School:
Epsilon Camp (Colorado)

Middle School:
Math Path (Colorado)

High School:

Bay Area or nearby
AwesomeMath (UC Santa Cruz and Cornell University)
COSMOS (UC Davis)
SUMaC (Stanford)
Math Zoom Summer Camp (Cal Poly Pomona and Rutgers)

Abroad
Modern Mathematics - International Summer School for Students (Jacobs University, Bremen, Germany)

Elsewhere
Candada/USA Math Camp (Mount Holyoke College in South Hadley, MA)
Bright Math Camp
Summer Program for Women in Mathematics (Princeton)
Hampshire College Summer Studies in Mathematics
MOSP USA team preparation for the IMO
PROMYS (Boston University)
The Ross Program
Young Scholars Program
Research Science Institute (most advanced in research)
All Girls/All Math
International Math Summer School (Germany) (brochure)

 

American Math Competitions
AIME
ARML
Canadian Math Competition
International Math Olympiad
Mrandelbrot Competition
MATHCOUNTS
Putnam Competition
USA Math Talent Search
USAMO
Math Kangaroo
ABACUS
MOEMS
North American Computational Linguistics Olympiad
The Stanford Math Tournament
ProCo - High School Programming Contest at Stanford

Mathematical Sciences Research Institute
Pacific Institute for Mathematical Sciences
American Institute of Mathematics
The Clay Math Institute
American Mathematical Society
Mathematical Association of America

Mathematical Reflections
Notices of the American Mathematical Society
American Mathematical Monthly

MSRI National Conference
AMS/MAA Conference in New Orleans

MathProPress
ProblemCorner
Art of Problem Solving
MathLinks
IMOmath