Sphere Online Judge

Sphere Online Judge (http://www.spoj.pl) is an automatically judged programming competition site. The main part is an ongoing contest to solve the most (and the most difficult) problems for a total score. A great variety of programming languages are supported, including Prolog, Scheme, Smalltalk and some esoteric languages.

The system was originally created for judging the work of students in some Polish universities. Part of the long-term vision of the site is to allow users to create and run their own programming competitions with a great deal of flexibility. A longer explanation is at http://www.spoj.pl/forum/viewtopic.php?t=133&sid=686585003af47983a9a0a5b8d665c6dd

See also the ComputerLanguageBenchmarksGame.