I've been lurking around this site for a while now as a non-member, reading through the Main Series list in order (currently on SCP-918). I'll probably lurk for a bit more before you see anything besides votes from me. Just playin' it cool.
Found the site through, of all things, an MSPaintAdventures reference (the object that becomes something least useful to a given situation when you try to use it; like the key/guns from Problem Sleuth).
Also, when I decided to read through the logs and started with the SCP-001 hub page, I just about crapped myself when I scrolled to that "memetic kill agent" picture after reading those serious-sounding authentification warnings. Was pretty much hooked after that.
EDIT: Of course. It had to happen on my first post. I usually don't get that wrong, I swear -_-