Gives you an opportunity to take on a leadership role you may not be privy to if you are a junior staff member at you full time gig. Since I have been working professional for less than three years, I am still pretty low on the totem pole in my day job. I succeeded in getting "assistant" out of my job title, but I still have a supportive role to my superiors. I am able to take on a leadership role I would not yet be considered for because of my lack of work experience for the non profit I volunteer for. I am currently a member of a board of directors of a non profit that two friends started in my hometown and lead a committee that has duties that definitely translate to applicable work experience.
Gives you an opportunity to add meaningful work experience to your resume. I have developed writing samples and lead projects for both of the non profits I have volunteered for that are now on my resume. Doing things such as leading a committee, planning events, writing media and marketing materials, among other things definitely belong on my resume. Whatever your skills are: writing, planning events, designing websites, networking, fundraising, mentoring or teaching youth, cooking...you see where I'm going with this, we all have skills that could be very useful to a non profit organization and could also help move your career along.
Offers opportunities to network with seasoned professionals...this could translate to a job opportunity. Whenever I have the opportunity, I chat up professionals that I meet at conferences or other settings and tell them about what I am doing for the non profit. Sometimes seasoned professionals can be inspired to donate time or money or even mentor you so you can make a greater impact to the organization or cause you are volunteering for. I believe that networking is about helping each other out, not waiting to contact someone when you need something like a job, for more info about networking, I would suggest reading the book, Never Eat Alone which I had heard about from Ginger over at
Girls Just Wanna Have Funds a few months back. Build these relationships now and they could later translate to a job or introductions to other professionals.
Makes you feel warm and fuzzy inside. Making a difference in your local community or on a national or global scale can make you feel good about yourself. Giving back is a good feeling you don't just have to save up for the holiday season, you can feel good about giving back any time of the year. Yes, I could probably find freelance gigs that pay me to do some of the things I do for the non profits, but making money is not what drives me to do what I do, its getting that warm, fuzzy feeling that I am making a difference (be it large or small) in someone's life.