Usenet nerd, here. Also, Prodigy nerd, here (though I only had access to Prodigy via a friend... and as a result I was always left wanting more).
Anyway, this may surprise some folks, but I had little interest in online discussions about video games back then. For me, it was all about music, fanzines, politics-lite, toys, movies, books, etc. etc.
The best discussions were about short-lived toy lines, though. There were lots of other folks who had had "Legions of the Universe" (I think that is what they were called) when they were younger and it was funny as hell to talk about it. I still think it was a kool toyline, but until writing this post I couldn't remember what they were called! Thanks nodtveidt for stirring up my stagnant brain cells! I can't believe I remembered what they were called just now (I've tried many times over the years since then).
OK, those weren't the best discussions, but they stand out now (in 2007) because I can't find anyone else who remembers the likes of Sprial Zone, Legions of the Universe, etc. I also loved finding out all I could about The Human League! Ha!