Started out on rec.games.video.arcade.collecting in the mid 90's, that group is a ghost town now. Made my first post to RGP in 1997, when I got my first pin. It was appropriately titled "how do I open my pin". Lurked for a few years on KLOV, before I finally registered in 2007. I found Pinside a year or so ago and joined.
I visit RGP, KLOV, and Pinside pretty much everyday now. They all have their good and bad points, and figuring those out is the key for getting the most out of them. I collect both vids and pins so between those three I pretty much have everything covered.