Codejudge is cool system to host coding competitions, something very similar to ICPC or like the Codechef website. Only better, because you can hack on Codejudge to customise it and run it from anywhere, even from your system!
Codejudge is hell easy to setup. The instructions are given here.
Codejudge is still in its infant stages of development. If you find any bugs or security loopholes in Codejudge please do report them here. Or better still, fork Codejudge on Github and start hacking on it. I'll be waiting for your pull request.