ACM-ICPC World Finals

http://cm.baylor.edu/welcome.icpc

ACM-ICPC Problem Archive

http://cii-judge.baylor.edu/

Topcoder www.topcoder.com

Sphere online judge www.spoj.pl

TImus online judge  acm.timus.ru

ACM russian online judge http://acm.sgu.ru/index.php

Algorithmist —http://www.algorithmist.com/index.php/Programming_Contest_Calendar

OPCcalendar — http://www.opccalendar.com/index/calendar/

University of Valladolid's

UVa Online Judge

The Annual Berkeley Programming Contest

http://www.inf.bme.hu/contest/tasks/

http://acm.hdu.edu.cn/contests/contest_list.php?type=scheduled

http://acm.hit.edu.cn/ojs/contest_index.php

http://acm.jlu.edu.cn/joj/contests.php

http://acm.pku.edu.cn/JudgeOnline/contests

http://acm.sgu.ru/

http://acm.sharif.edu/arbiter/environment/list.jsf

http://acm.timus.ru/schedule.aspx

http://acm.tju.edu.cn/toj/

http://acm.uva.es/archive/nuevoportal/contests/contest/

http://acm.uva.es/contest/nextf.html

http://acm.whu.edu.cn/noah/contest/contestList.jsp

http://acm.zju.edu.cn/onlinejudge/showContests.do

http://codechef.com

http://codecup.nl/competitionlist.php

http://contest.inoi.ir

http://hsin.hr/coci/

http://ioinformatics.org/

http://ipsc.ksp.sk/

http://neerc.ifmo.ru/trains

http://olympiad.cs.uct.ac.za/online-contest.html

http://opc.shaastra.org/

http://rabbit.eng.miami.edu/contest/

http://recmath.org/contest/

http://spoj.pl

http://technovanza.org/?p=360

http://usaco.org/

http://www.iarcs.org.in/inoi/programming-contest.php

http://www.techpragati.com/coding.aspx

http://www.topcoder.com/tc?module=Static&d1=calendar&d2=thisMonth

http://www.z-trening.com

http://www.codechef.com/COOK01/

http://icfpcontest.org/

http://cplus.about.com/od/glossary/a/ten-contests.htm

http://www.azspcs.net/

http://www.puzzles.com/