Detailed is tricky, because if I set the wayback machine that far back you have to realize there were only a handful of reef related resources on the net back then. Because of that almost everyone who took part in one took part in them all, which means a lot of things get all intertwined. To an extent things happened here because of other things that happened on compuserve's fish forum, aqualink, Rick Martin's reef-l mailing list, my own [email protected] listserv
[Edit: Gah! I forgot Albert Thiel's list/site, that's how long it's been]... all pretty boring stuff to most, I'd think, especially as most of the folks involved aren't active on-line or in the hobby anymore, and many haven't been in -years- so not even their names are familiar anymore.
But the short version is reefs.org started out as the #reefs channel in IRC, and it's real time scheduled talks given by various authors were it's main draw and attraction. Over time the web site portion of reefs.org got developed, with the biggest change being the addition of the message board back in... 1998? I think.