Boring story; I've always been here since OB and then SL4. (Ironically, I think I originally came to the SIAI site way back in 2003 or 2004 via StumbleUpon.)
Likewise, I was following OB, which I started reading about a month after it started; I have no memory of how I found OB.
I was reflecting the other day about how I learned about LessWrong. As best as I can recall/retrace, I learned about LessWrong from gwern, who I met in the #wikipedia IRC channel via an essentially chance meeting. I'm wondering how typical my experience is. How did you come to LessWrong?
EDIT: Optional follow-up question: Do you think that we (the community) are doing enough to bring in new users to LessWrong? If not, what do you think could be done to increase awareness of LessWrong amongst potential rationalists?