Well, track cycling is not singlespeed because it's fixed - and fixed is a completely different bag of fish that has a zillion other websites and forums that are solely dedicated to fixed, and wouldn't want to know about anything that involved a freewheel. Fixed doesn't count.
BMX is, I suppose, singlespeed (being done with a single freewheel), but it's not really 'cycling', is it? I'm a big fan of BMX, and used to race in the early eighties myself, but it probably doesn't relate too closely to the type of riding that most viewers of this site are involved in. And, we certainly can't include all those hoody teenagers on scruffy little bikes down the town as singlespeeders. BMX doesn't count.
Ladies who go mountain biking, or ride on the road - as 'cyclists' or cycling enthusiasts - with a single freewheel bike, are what I had in mind when I asked the question. So, it would seem that we have yet to find any real lady singlespeeders.
"Gears are like eyes or testicles. Having more than one is an unnecessary luxury." Elvis A. Presley