I don't think anything makes me happier than seeing — and contributing to — projects that are open, free, community-driven and positive in their impact.
OpenStreetMap, Wikipedia, the Mozilla Foundation, effective altruism, Khan Academy are but a few examples of such projects.
Beyond that, I hope I never stop marvelling at knowledge, at biodiversity, or at a starry sky.
I have also gathered a handful of works that marked and inspired me deeply: