Just that, really.
I definitely have a few names that I recognise when I see them, but not enough to remember how/in what context I've encountered them before.
I've noticed recently a few people namechecking other posters: "So-and-so will be along in a minute to say X" or "Such-and-such usually has a good idea of things like that".
There seem to be so many posters here, I'm amazed at how some people seem to keep track, not just of familiar names but of personalities, too.
Do you?