Somewhat related thread. The people I personally knew before joining KYM are listed in that thread.
As for the reason as to how I found and why I joined KYM, it was all thanks to those awesome YouTube episodes of theirs.
You see, before I even knew what KYM was, I was just a humble person who researched all he could about internet memes when he was bored. Internet memes just really fascinated me for what they were.
One faithful day, after typing "meme" on YouTube, I discovered several of Rocketboom's videos and I tried to see if the series had its own website. Guess what I found a few minutes later.
Anyways, I didn't plan on joining the site until I saw a specific thread on the forums which, you could say, hurt my feelings. It just clicked in my mind that I had to join to try to straighten things out and give people proper facts about the certain subject at hand. And, before I knew it, I was part of the community.
Early on, I only submitted images on a large scale but after a while I took a crack at researching for memes much more seriously than the simple check-this-website-to-see-what-info-I-can-find-about-this-meme-and-see-if-it-interests-me kind of attitude I had towards researching. The rest is history.