I had once set problems for Internal contest of our college IIT Kanpur. See link http://www2.cse.iitk.ac.in/judge/public/. I had also added the problems on spoj http://www.spoj.com/problems/IITKWPCA/ to http://www.spoj.com/problems/IITKWPO/. Please Try them :)

I liked the problem C http://www.spoj.com/problems/IITKWPCC/ most. None of the teams was able to solve this during the contest. After adding on spoj, I was expecting that lot of people will try to solve this problem. But not a lot of people have done so. So It kind of looks bad when your most loved problem does not get many users to attempt. So I request you to attempt the problem :). I am sure that you will love it :)