Yes I have. It was on another website forum. I figured out who she was based on her ID name and some details she mentioned in her post. It was a bit weird because I found out something about her that was not common knowledge and I had to be careful not to let it slip whenever I spoke to her after that.
Also recognised a girl I worked with on line from something she said in a particular forum. Was I amazed or what!? Har, Har. I'm still giggling about it now 10 years later!
I was on holiday in France and got talking to a guy from the UK and recognised him from another very large forum by the story he was telling. We had a good laugh about it but I think we were both surprised.
You expect some of this in Ireland with the small population and the limited number of forum contributers but goes to show it really is a small world.