There is a strong overlap in my RL friends, tastes and discussion topics and my online ones, so all this feels a little different to me. I view most fannish fora as layers of one of those three dimensional chess sets from original Trek (and elsewhere, I'm sure). Each layer is a medium of discussion, each participant a piece, and each conversation a move.

The tiers of my personal chess board are:
LJ
mailing lists
realtime chats associated with those mailing lists
private e-mail
Y!M and AIM
conversations with RL friends
conventions
FAP and similarly well known sites that have discussion boards


I see usenet as separate since I haven't been on there much in years, but when I was a 'regular' on alt.teens (oh, the shame!), I saw all of usenet in much the same way, only each group was a layer of the chess board.


I like this representation because I feel it captures the lateral movement of discussions (from friend to friend on lj, for example), but also the strange teleporting abilities my friends seem to have. I am forever running into people I used to know from some anime fandom list in realtime Harry Potter H/D discussions. I am also forever running into RL friends in odd fannish places.