To continue the previous post, if you are interested in sports scheduling, there are a number of sites that you could visit. 

First, Michael Trick's website is a treasure trove of information on sports scheduling and the optimization algorithms that are used to solve them.  I highly recommend reading the survey papers on round-robin scheduling and constraint programming.

Second, this site written by a researcher at University of Onsabrück that is an exhaustive catalog of sports scheduling publications, organized by type of competition and problem, the type of solution method, and the sport.  The majority of papers explored scheduling issues in soccer, which was a little surprising to me.