That's an interesting topic, alright. Here's a short history of my own involvement with online discussion forums.
I've been online since 1991, beginning with Usenet Newsgroups. Several of the boards on which I often discussed religious topics, and in particular argued with JWs, were talk.religion.misc, soc.religion and soc.religion.christian. I met a number of people there, including my present wife. I wrote many essays on the JWs and related topics, most of which were the basis for long posts on these Newsgroups.
I knew by 1993 that the Net (the Web wasn't even around back then) would be an extremely powerful force against the Watchtower Society, since so much information was freely available and people could, in private, find out all sorts of things the Society didn't want them to know. They could also easily communicate and share ideas and experiences, something that has been extremely valuable to many ex-JWs in getting their heads on straight.
By about 1994, many of the JW-critics I had become friendly with subscribed to an email-based listserve called jesus-witnesses. Many of the JWs who were fairly vocal on the Usenet boards came on this list for awhile, but most eventually gave up.
In 1994 the Web started up in popular consciousness, and one of the JWs I had helped to get out of the JW cult decided to start a website ostensibly for JWs. It was called "Associated Jehovah's Witnesses for Reform", and it attracted a good many practicing JWs. The site owner had some good laughs at their expense. I believe it existed for only a year or so.
About this time several of us who had become friendly on Usenet started up a private email list we called "Philia". Eventually this came to have more than 200 subscribers off and on. I met many ex-JWs there, and some have remained my close friends. A popular website's owner, Timothy Campbell, got on the Philia list and soon started the website "Beyond Jehovah's Witnesses", which has done a great deal of good. Another extremely useful website, "Research on the Watchtower", was started by a Philia subscriber. He used many of my long essays to start, and then latched on to posts from the H2O website for some years. Another friend, Jan Haugland, started a website that dealt with Watchtower history. Yet another, Kent Steinhaug, started the website "Watchtower Observer" which became the Grandaddy of big JW-critical sites. A number of other Philia subscribers started their own websites.
About 1997 the H2O website started up, run by an apparent JW who had ideas of reform. I soon joined, and not long after that quit posting on the jesus-witnesses list. H2O attracted plenty of interesting people, including some rabid anti-JWs and rabid JW apologists. It was kind of a free-for-all, and you had to be pretty thick skinned to enjoy the fray. One JW who called himself Lee Elder figured out, as a result of discussions on H2O, that the Society's blood transfusion ban was ridiculous and unscriptural. He then started the website "Associated Jehovah's Witnesses for Reform on Blood". Of course, a number of H2O posters eventually started their own websites. Many people who at first came on H2O as JW defenders eventually saw the light and quit the cult.
By 2001, H2O was becoming untenable as a good discussion forum since the site owner wanted to control how the many free spirits who posted there expressed themselves. So in early 2001, most posters left and began posting here on Simon's board.
During the late 1990s, AOL was a fairly active forum for JWs and their critics. I subscribed for awhile around 1996, but soon lost interest since the posting environment was extremely inefficient, and terribly restrictive. AOL sucks.
Dozens of forums have been created since the early Usenet Newsgroup discussions, most of which I have little or no knowledge of. It'll be an interesting task for you to find out their history.
AlanF