Stranger on a Train, that is! 
From everything I’ve seen in his posts, he knows a ridiculous amount of detail about dang near everything. So my current pondering is trying to figure out how he does it…
Brain implant linking him directly to Wikipedia?
Photographic memory of every book he’s ever read…and he lives in the Library of Congress?
Cecil’s lost brother?
'Tis more machine than man.
This isn’t a good idea. It could malfunction, go into reverse and force him to think whatever people edit into it.
Has he seen this thread? Someone PM him!
Sometimes the police arrest him just so they can have a conversation with him.
He’s a righteous dude.
In my short time here, I’ve narrowed it down to two possibilities: 1) he’s really ten people posting under one user name; 2) he’s ten times smarter than me. One of these is more likely than the other, I fear.
The SDMB has a fair few people who are nearly as good as Cecil. Polycarp and Qadgop to name but two. Gfactor’s in the running too.
Unless I’m mistaken, Stranger on a Train suffers from RFS* syndrome. There are a double handful of Dopers who do. 
Or he could be incredibly good at the fine art of Baffling Them with Bullshit.
I kid…I kid…he is a gem and a credit to the boards.
Not only does he appear to have wide-ranging, near-eidetic recall of technical arcana, but he is evidently a fine woodsman with a keen sense of culture who cooks. (And he’s single? Is this a hoax, socal girls?)
I’m just glad he doesn’t play against me in the Mafia games!!
He’s a true Renaissance man, from what I can gather.
Plus, I use his recipe for making pizza dough. I always remember good food.
What?! We need to circulate a memo or somethin’. No way a fine specimen like this should go unhindered. I mean -loved! Unloved!
I think I found his pic here.
[sub]Sorry, couldn’t resist[/sub]
Count me in for being impressed. I recall him saying that he writes extemporaneously, and I have to believe it. 'Cause if I wrote that much, I’d never get any work done (well, I’m unemployed, and I’m sure I get less done than Stranger). He sure as hell writes pretty good for some damn scientist nerd. Plus, he’s got pretty good taste in cinema, and I seem to recall he’s a huge fan of Toyota FJ40’s.
“Twisted and evil.”
There is still good him in him, though, I know. 
Seriously, thanks for the accolades. (And thanks for pointing out the thread to me, lieu.) I fear my reputation may have overextended me, though. I’d like to think I’m halfway to smart but not half as smart as half of you think I am, and half less again than the other half opine. It is the fact that in no small measure my vast array of technical and refernence literature which I consult with serious frequency must share some of the kudos awarded. And ivylass, it is the sign of true genius to excel in the art of bafflement with excrement, which further demonstrates that I miss the mark of genius by at least a few notches; I’ve been called out by my betters on more than a few occasions and I hope that I have had the graciousness to recant, or at least skulk away silently. In addition to the names Quartz mentions, I think that Q.E.D., Chronos, Voyager, Darwin’s Finch, bibliophage, Colibri, Una Persson, and many others whose names I am currently unable to recall but will remember with regretful but delinquent urgency as I wake in a cold sweat at 2 a.m. far exceed my knowledge in their own areas of expertise and likely elsewhere.
However, Wile E, that’s clearly not me. I have brown hair. Otherwise, it is an astonishingly close resemblance.
Again, thanks to all. It has brightened a day otherwise filled with soul-devouring, thankless work for my corporate masters.
Stranger
Oh, hey! Why, just this very evening before seeing this thread I was marveling (yes-marveling!) at how common-sensical and intelligent and well-spoken the subject of this thread is. I guess I hadn’t really noticed him before, not that I had anything against him- but just so happens that lately the planets aligned just right, the barometric pressure was at just the right point, and we’d posted in the same couple of threads… and I noticed him. And I was impressed. I thought, wow- he always knows just the right thing to say with just about any subject.
Serendipitous thread.
I taught him everything he knows.
I would also like to nominate John Mace, Colibri, and Chronos (amongst many others) to the list. I swear Mace is some kind of fuckin computer.
As a bona fide Rocket Scientist, I am always happy when Stranger on a Train posts in the GQ aerospace threads, because it means I get to learn something about rockets that I probably didn’t know. It’s like getting my Master’s in Aerospace Engineering… three minutes at a time.