Here is a list of things an Operation Research professional can do for fun. If you can think of any more please do not hesitate to add in the comments section.
1. Project Euler
This is one of my favorite problem solving websites. It is not explicitly Operations Research as more applied mathematics. Yet it is very interesting to try to determine ways to solve some mathematical, numerical, and logical word problems. It will more than likely require the use of some computer programming skills.
2. Netflix Prize
A couple of years ago Netflix, the movie DVD-to-the-door rental company, decided to open up to the public ways to improve its movie recommendation engine. The rules were very straight forward. Given a user defined list of movies find similar movies that the Netflix users might pick. Netflix would provide a pretty comprehensive data set of user lists. Numerous people and organizations have provided suggestions. There is even a leaderboard based on RMSE. Oh yea, and the prize is $1,000,000. That ought to get you interested.
3. Volunteering with High School Operations Research
High School OR is a volunteer organization that helps to bring Operations Research to the high school level. High School OR develops and maintains workshops for high school teachers so that they may use Operations Research in the classroom. This is a great way to get the Operations Research profession to the younger generations. High School Operations Research is sponsored by INFORMS.
4. Math tutoring
The Operations Research professional can use their skills to help elementary, high school and even college students in mathematics. This can be an excellent way to contribute to the community. Perhaps even to make a little more money on the side. There will always be a need to provide math assistance since students are subjected to more and more testing. There can be a great intrinsic reward to helping those achieve their fullest potential. This can also be a great way to show how math can lead to a future profession, specifically Operations Research.
5. Contribute at the COIN-OR project
Open source software is growing in the Operations Research community. Paraphrasing from the COIN-OR website...
COIN-OR's goal is to help gather a community for software in Operations Research what open literature in the past did for mathematics.There are many ways to help with COIN-OR open source projects. I describe these ways in an IEOR Tools post Top 5 Things to Get Involved with Open Source in Operations Research. There are many ways to contribute to Open Source projects. You need not be a programmer to get involved. You may be a debugger, tester, or even help with documentation. The ways are limitless to get involved. Open Source in Operations Research can be a fun way to learn new ways to solve those classic optimization problems.