Sites

Math Olympiad for Elementary Schools (Popularity: )
http://www.moems.org/
Contest open to all students grade 8 to 4. Offers resources for students and school mathematics clubs.

Australian Primary Schools Mathematical Olympiads Inc. (Popularity: )
http://www.apsmo.info/
Open to primary schools in Australia, New Zealand and surrounding countries.

Crux Mathematicorum with Mathematical Mayhem (Popularity: )
http://journals.cms.math.ca/CRUX/
Problem-solving journal at the senior secondary and university undergraduate levels.

The Continental Mathematics League and The National Olympiads (Popularity: )
http://www.continentalmathleague.hostrack.com/
CML offers a series of math meets for grades 2-9, a calculus league for the high school, and a Java computer contest.

American Regions Math League (ARML) (Popularity: )
http://www.arml.com/
Results and past problems for the ARML, an annual national competition.

Valentin Vornicu's MathLinks (Popularity: )
http://www.mathlinks.ro
Math Olympiad Problem Solving site with a weekly contest, resembling IMO in difficulty, with a large math forum and downloadable materials.

Putnam Exam Information (Popularity: )
http://www.math.harvard.edu/putnam/
Results from the Putnam competition, old exams, and problem archives. Includes problem of the day, selected from over 540 different Putnam, National or International Olympiad problems.

Ravi Vakil (Stanford) (Popularity: )
http://math.stanford.edu/~vakil/putnam03/
Training resources for the Putnam competition. Practice problems, notes on mathematical theories, and recommended reading.

Mathematics Archives (Popularity: )
http://archives.math.utk.edu/contests
links to contests, problem sets, journals sites.

Greg Martin (UBC) (Popularity: )
http://www.math.ubc.ca/~gerg/teaching/putnam/
Syllabus and practice problems from Rajiv Gupta and Greg Martin's Putnam practice sessions.

Stanford Math Tournament (Popularity: )
http://www.stanford.edu/group/sumo/smt/
Annual math event sponsored by the Stanford Mathematics Department. Site contains results, past tests and solutions.

American Mathematics Competitions (Popularity: )
http://www.unl.edu/amc/
Organization that administers the AMC, the AIME, and the USAMO, with information about the contests, math problem archives, recommended reading lists, and other resources for students interested in mathematics.

Math Competitions in USA (Popularity: )
http://www.albanyconsort.com/contests/contests.html
Sample problems, information and links from multiple contests.

Vojtech Jarnik Mathematical Competition (Popularity: )
http://prf.osu.cz/kma/dokumenty/vjaimc/vjaimc.html
Held at the University of Ostrava every year in March or April, open to university students. Site includes contest rules, results, and past problems and solutions.

Noetic Learning Math Contest (Popularity: )
http://www.noetic-learning.com/mathcontest
Monthly contest for students in grades 2 to 5.

Problem Solving References & Resources (Popularity: )
http://www.math.hmc.edu/~ajb/PCMI/problem_solve.html
Overview of seminars oriented towards problem solving. Includes sample problem sets, list of online resources, college mathematics journals, and useful books. Maintained by Andrew Bernoff (Harvey Mudd College).

Australian Mathematics Trust (Popularity: )
http://www.amt.canberra.edu.au/
Sponsors a number of competitions in the Australian continent.

SMS: Singapore Mathematical Olympiad (Popularity: )
http://sms.math.nus.edu.sg/competitions/CompetitionHomePage.aspx
The largest and oldest mathematics competition in Singapore. Contains schuedule, results, rules, and photo gallery.

Problem Writing For Mathematics Competitions (Popularity: )
http://www.virtu-software.com/math/
Mathematics problems for middle school and high school math competitions with topics range from algebra and geometry to probability and trigonometry.

Math League (Popularity: )
http://www.mathleague.com
Specializes in math contests, books, and computer software designed for students from the 4th grade through high school.