Ask HN: What have you discovered on Hacker News?

This may sound silly, but I learnt about the worlds smallest nerf gun and I found the science of it really fascinating. https://m.youtube.com/watch?v=9c2NqlUWZfo

I also discovered guess the correlation which I’ve had a lot of fun with https://www.guessthecorrelation.com/

I also learned some commands for the command line that I did not previously know.

Ruby Ruby on Rails CakePHP OkCupid (it was interesting seeing the first blog post about it and then seeing it grow) Reddit I'm pretty sure I learned of a few open source games from here.

The occasional event or link to a conference.