besides open source software, I make my largest annual donation to Books Through Bars in NYC, an all volunteer-run group that sends free, donated books to incarcerated people across the country.
Other than financial contributions, I consider myself a supporter (with bug reports, code, documentation, sometimes PRs) of Processing and p5.js, fish shell (answering questions on the various stackoverflows, when im not asking them myself), pyradio (writing some tutorials), and various other small stuff