What SDMB members have you encountered in other places on the Net? In my case
I know Biffy the Elephant Shrew from the Usenet board rec.arts.comics.strips. I
thought I knew Hypnotoad from my sim racing haunts but it turns out he’s two
different people.
I’ve seen dopers over on FARK.
I first met Guinastasia at Customers Suck years ago. I’m pretty sure she is the reason I discovered the Dope. Thanks, Guin!
A few weeks ago I came across some of Inigo Montoya’s photos at PBase. I like Cube Henge the best. Simple yet fascinating!
I come across Ellis Dee’s posts over at the NY Giants message board now and then.
I come across matt_mcl’s posts on LJ while surfing betimes. 
Not sure her username, but I read a blog by a Las Vegas cocktail waitress and she says she posts here all the time.
I suspect that a few Dopers posteed on Grudge Match, but this is based on writing style, & I cannot prove it.
I have, under my real name (my first name is “Ryan-” that’s all I’m giving away). I was younger and stupider then.
I know at least one other person here that is also a member on BoardGameGeek , but I’m sure as many times as I have seen the Geek linked here, there must be more.
I’m not sure of his username or if he just lurks here, but a slim, citrusy friend of mine says I turned him on to the SDMB by discussing it over at another board. It involves a sufficiently geeky hobby that I’d rather not own up to it.
Also, there’s a reason Leaper always calls me ‘Souled,’ and it involves IRC #mtg.
My nick descends from E-League MTG, so I may remember you, Ace.
I also know rjung from TF Fandom. But I don’t think he knows me.
I don’t think he posts here any more, but Achernar overlapped me by a year in the astronomy department of my undergrad university (and we both joined here independantly; neither introduced the other to the site).
And I once encountered a reference to “the infamous OpalCat” (yes, I think it was phrased that way) somewhere completely unrelated to the Dope, but I don’t recall where it was.
I’d seen both Guin and, a few times, wring over at snopes long before I’d ever even heard of the Dope.
I know there’s some metafilter crossover. I only read there, though.
I knew TubaDiva ever so slightly, back on AOL when we were both hosts of different fora. (She of the Dope, obviously, me somewhere else.) We have friends in common, though.
Cheers,
G
I have. Only once, I believe.
Evil Death is banned now, but I knew him from Usenet before I knew this place existed.
I also know Biffy The Elephant Shrew from posts he made in a Frank Zappa forum. We don’t know each other personally, although we’ve had some interaction in threads here. I asked if it was him (how many people could have chosen that username?) and he confirmed that it was.
I have seen a Shirley Ujest over at the Knitty.com forums, though I’m not sure if it’s the same person as here.
A 6 degrees of separation kind of thing then.
I know that Paul in Saudi writes and edits Wikipedia articles.