one of the things i wrote a long time ago was the "save the world" feature that is often seen on private bittorrent trackers.
for those who are unaware, there are a family of sites (originating at https://thehungersite.greatergood.com/) where if you visit them, and click a single button, you are donating real, actual money towards their cause.
i wrote a small page, that by clicking a series of buttons sending you to thehungersite, thebreastcancersite, theautismsite, etc etc (and on the good-will you clicked the button on their webpage), you'd be rewarded a small amount of upload credit. i allowed users to do this once a day. provided the user was persistent, it can add up after a while. it's super helpful for new users who need to build ratio, it goes to a good cause, and takes 30 seconds to do. i added this feature maybe 15 years ago and it's still there to this day, with people still using it. (don't ask me why a 15+ year old bittorrent tracker is still online, either.)
along with putting it on my own site, i published the code to a forum dedicated to adding features to the base install. and after all these years, i'm still seeing it get used in some incarnation on other trackers. i'm hoping that my small little contribution has made some form of positive impact in the world of evil, no-good copyright infringement.