I found out about Paul Graham through comp.lang.lisp. Way back in my freshman summer of college, I had an internship where I didn't really have very much or very important work to do, so I spent a lot of it reading about Lisp. Graham's name came up a lot, and his essays were interesting. Ended up reading On Lisp after that.

I moved over to Hacker News from Reddit the day it became publicly available.