Student Competitions

I would like to create a comprehensive list of student competitions for my teachers. By competition, I mean a regular activity or event where students compete against other schools or other students. Examples are the math Olympics, geography-bee, spelling-bee, etc.

math 1-on-1: http://www.artofproblemsolving.com/Edutainment/g1/Pages/TOS.php
programming: http://projecteuler.net/
math & spelling 1-on-1: http://projecteuler.net/