A couple of years ago, there were heavy floods in the city I live in, many homes in the low lying areas got severely affected. There was a lot of community activity in organizing help for those whose houses got affected. I participated in them - tore up walls and floors that got wet, crawled under mobile homes and removed insulation, helped people move stuff.
Another time, I participated in a school kids career counseling event (it was a one day event)
For quite some time, I used to attend the meetings of a local NGO involved with energy conservation. Helped them collect over 200 signatures for a petition. The petition was presented to the Governor of Indiana for increasing energy efficiency of government buildings. I think I was the highest or the second highest collector of signatures.
Also helped them a bit with their website - back then my skills were too basic though.
I also keep cheerleading my mom :). She helps a few kids with their school/college education. There have been times when some abuse those good intentions and trust and she gets disappointed. I keep telling her to soldier on (not that she can't without me telling) and that these are opportunities to learn how to select better.
I wish I could participate more often. Hopefully, once my goals are on track and self-sustainable...