Putnam Exam Information
- 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.
- http://www.math.harvard.edu/putnam/

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

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

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

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

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

American Mathematics Competitions
- 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.
- http://www.unl.edu/amc/