Volunteering doesn't have to be earth-shattering or all-time consuming either.
I collect blankets, newspapers and dog food for some of the local animal shelters. Extremely easy to do, doesn't take that much time and the shelters really appreciate these donations. During power outages, my wife and I will run down to the shelters with coffee, donuts, maybe some soup for the people who work at the shelters, they really appreciate that.
And don't overlook job fairs at your local schools. If you hear of any, giving an hour or two is quite easy. Most kids are fascinated by pilots, and what pilot doesn't love talking about their job?
That's an easy, quick two suggestions for the volunteer route. The main purpose though, as it was explained to me, was the airlines are looking for sense of community, their hiring the "whole" person, not just something with thousands of hours.
Nearly everyone that applies at an airline is qualified, having 10,000 hours doesn't make you more qualified than someone who has 5,000 hours, so what sets the two apart? Education, volunteerism, type ratings, continuing education, this is what the airlines now are looking for.
Think about in these terms: the airlines are doing the exact same thing! JetBlue touts their community involvement, Alaska their "Green Initiatives", etc. Why? It has nothing to do with flying and everything to do with gaining the slightest competitive edge.
Give yourself a competitive edge and volunteer for a couple of hours a month!
Best of luck!