I am sure that all of us have some unknown skill that we have always wanted to add to a resume just because it looks good. In today's tight job market, employers are looking for people who can do more than just the job they are hired for. In essence, they want to hire a jack of all trades for a position.
Decide what looks good
If you played water polo in college, that is probably not going to secure you a job on Wall Street. If, however, you coached for the city league basketball team, it might help you secure a job at a local high school. Coaching ball exhibits that you are able to deal with young people in organized activities.
Organize your extra info
Once you decide what looks good, you can add sections to your resume like Civic Responsibilities, Volunteer Activities and even Additional Information just so I have somewhere to list this information. One friend was applying for a job that involved a lot of writing so he added an additional information section where he added facts about two articles he had published.
Your cover letter is a good place to mention a skill and then expand on it in your resume. If you are applying for a very civic-minded or non-profit organization and you have volunteered or participated in local civic activities then add a section on your resume to include that information.
What is your goal?
Your main goal should be to create a resume and a cover letter that shows you are uniquely qualified for the position in question and that you possess skills outside of the everyday applicant. You also want your resume to show that if greater demands were put on your for different tasks, you could easily handle them.
Finally, you want to appear to be a dynamic and interesting individual that will contribute to a company as a new employee. You should only list information that can somehow be considered applicable to the job, to you as an applicant or to the company in general. You are trying to create a positive picture with your additional information.
Once you add your unrelated information, sit back and read your resume objectively. If you laugh out loud then it might mean you should remove that info. If it makes you think twice or think how neat is that, then the information is probably warranted and should stay on your resume.
So, whether you are black belt in martial arts or were in the ROTC in high school, use whatever skills that you have developed outside your work experience to make yourself appear to be the most competent and sought-after applicant for the job.