And I guess I better go first...
I became fascinated with the Olympic Games as a little kid and started reading into the history of the Games. I'd spent plenty of time in libraries looking through histories/newspapers etc to discover some facts from the past I was interested in, but was surprised not to find more books covering the history of sports. Once, when I ordered a specialist historical book from overseas the author replied that if I had a copy of an Australian historical book (which I did) and sent him photocopies of it, he would send me his book for free.
When he sent me the free book, he also asked a few questions about a particular Australian athlete of the 1940s/1950s. I was soon down the library, looking through newspapers and sending him this 'unknown' info. This was before the days of the internet, so this kind of research could take a long, long time, but it was a bit of a buzz to think I was rediscovering lost history.
Eventually as part of my research, I discovered that the official history of this sport in Australia was wrong (very wrong!) and set about to re-discover what the true facts were. The history of the sport for women was especially wrong, saying it had only started around 1927, whereas I found out that competitions had been held from the early 1900s and an official (amateur) body for women had been established not long after this. I also discovered a bunch of 'lost' world and national records of the time.
Eventually I wrote a revised history of the sport (athletics/track and field) which was published by the IAAF (equivalent of the ITF) and was even featured in newspapers around Australia in the lead-up to the 2000 Olympics. And when athletics published a new history of the sport a little later, I was mentioned and some of my historical facts were published in that.
While doing the athletics research, I'd get distracted by stories of tennis (and other things) in the newspapers, though I'd always assumed that the history of tennis (a much more popular sport in Australia) had been covered much better and was pretty much intact.
Of course, not so. And the coming of the internet made me realise how much tennis info was missing/not known. I couldn't believe that even GS results from the old days were largely unavailable until I came across BFTP.
Of course, as great as BFTP is, there is still plenty of missing info from the past. So - that's why I'm one of the geeks in here trying to put the jigsaw puzzle together!