I have an online friend that I met about five years ago in a forum for a popular children’s book series that was NOT Harry Potter.
Then, about a year ago, he thanks me for linking him to a thread here on the SDMB. I’m all like, “um…I didn’t link you to any thread…” So he goes back to his Livejournal and checks. The person who linked him to it was a friend of his from high school…and also a Doper that I’d noticed before.
Also, one of my SO’s friends may-or-may-not be a Doper. He does peruse the boards and columns, though, and has for quite some time, maybe a couple of years.
No one’ll’ve spotted me, though–this is the only place where I use “Angel of the Lord” as a handle. Pretty much everywhere else, I’m Sanji or SanjiKRhys.
I was a fan of BadAstronomy.com waaaaay before I was a Doper. Imagine my suprise and delight to discover that Phil Plait (The Bad Astronomer) was also a Doper. I felt so spiffy.
I can’t remember who it was exactly, but I remember seeing someone posting on the SDMB asking for help starting to learn some more maths - book reccomendations, etc. A couple days later I saw him post on sci.math with a similar OP and I thought “Oh. That’s whatsisname. Neat.”