Online Contests

Opentrains

• Opentrains Logins
• Opentrains Contests
• A complete list
• Official contest list

Yandex

• Yandex Contests

Open Cup

• opentrains
• Official Website
• List of all Open Cup contests

AtCoder

• AtCoder test cases
• Kenkoooo

TopCoder

• Contest Archive
• Problem Archive

Polish Contests

• Olimpiada Informatyczna
• Szkopuł
• OIOIOI

Training Camp

• List of all Petrozavodsk Contests

OI Contests

ICPC Contests

http://oj.qingyu.us/archive/icpc/