BNU Online Judge
Older releases on Google Code: http://code.google.com/p/bnuoj
An Online Judge system for Beijing Normal University, featuring following awesome functions
Basic online judge functions;
Virtual judge functions, including loads of OJs;
Replay contests and merge standings;
Contest with challenge sections, like Topcoder and Codeforces;
Problem categories, delicious for new comers.
And it's still developing!!