Being in the non-profit sector, I have some thoughts on this.
Would you have someone to drop by and build you a bridge to satisfy their community service?
If you do something like programming for some agency, take into account the long term cost of what you do. Putting up a site with a framework is quick, but will there be someone able to support updating the code in the months and years to follow?
For programming I'd go with open source contributions. (also you can put links to your work and add to your resume)
Tutoring is good, doesn’t have to be in high school, there are local community centers that are looking for people to put on workshops and such.