I've started thinking about drawing a similar thing, but in some cases I know people from a newsgroup first, or something similar. I'm thinking vague groups like RPGsoc people, oxnet people, AFP people, ucam.chat people - all those are fairly early groups in the food chain, so to speak, but even there there's a fair bit of overlap. And do I say I know people I met through ucam.chat via damerell (since it was he who introduced me to the group) or do I have the group as an entity of it's own? And what about the people I think of as vaguely AFP people who I didn't actually meet through AFP myself, but through others. And later groups are so much more complicated, and it gets harder to work out which set of people the link actually came from.
I suspect if I actually make the attempt. I'm going to end up with a strange cross between a directed graph and a Venn diagram, with lots of different colours. It's still the random collisions of two completely different sets that always make the small world syndrome so much fun. I wonder how on earth you could show those? And of course if you knew about them before they happened it wouldn't feel like small world syndrome any more. Perhaps by not getting round to it I'm giving some of you a chance to make the discoveries of connections yourself, rather than giving them all away.
Update: Of course the Mindmap thing is kind of linked, but it shows the closeness of various people to each other, and lets you begin to see vague groups, and I'm more interested in how they evolved and how well they match the groups I mentally file people under, IYSWIM.