I've often said that I truly can't conceptualize how many people are out there reading me. I see a number on my userinfo page, but my brain doesn't wrap around it. There's a core group of about a hundred of you who I've met/comment frequently, and that's what I picture when I picture The Public. That, I've said before.
But it's interesting to have that example, to realize that I honestly forget that someone's reading me when there's not two-way input.