How do you give back?

This thread [0] made me wonder: how do you give back to the community, be it tech, or otherwise, whether financially or with your time and talent? Open source contributions are the baseline, but I want to know about contributions beyond that, be they in meatspace or cyberspace.

I'd like to make this a recurring thread (hence, the title.)

[0] https://news.ycombinator.com/item?id=9781145