Competitive Programming Hall of Fame
— History of international championships
Petr Mitrichev's blog
— Algorithms Weekly by Petr Mitrichev
Google Coding Competitions Archive
— Unofficial archive
ICPC World Finals
— Unofficial ICPC standings
Is my problem new?
— Semantic search for competitive programming problems
Coding List: A Coders Calendar
— Unofficial CLIST android app
CF Analytics
— Chrome extension
AC Analytics
— Chrome extension
LeetCode Contest Rating Predictor
— Web application
OJ
— Online judge tools
Codeforces
Codechef
Leetcode