I’ll take you on, but I can go back to its NWA / Georgia Championship Wrestling days. Unfortunately, most of my knowledge comes only through TBS and the industry magazines (which were totally kayfabe) available at the time.
While I’m familiar with Georgia Championship Wrestling and Jim Crockett Promotions, you would probably win. I grew up on wrestling but I’ve not been watching for two or three years now and have thus forgotten a bit and, only being 24, most of my knowledge is fourth-hand or more and long after the fact in the first place.
On a specialist board, I’d be firmly in the middle of the pack and only claimed any expertise in this thread due to the dearth of topics relating to it.
Well, I am really knowledgeable about dog & cat breeds in general, but on many specific breeds, I’m sure there are plenty of people here who know more than I.
I know quite a bit about gemstones, but again, not sure if I could hold top rank hereabouts.
Someone (Guinastasia?) mentioned the Romanoffs and European royalty - mine would be specifically Louis XIV and Queen Victoria.
Other subjects on which I feel confident: Jimmy Buffett’s music, Due South seasons 1 & 2.
I’d like to think I’d be the resident board expert on botany, general ecology, caves and caving.
Bet not. 
I work at a place where Native Americans lived for 10,000 years, and I’ve picked up all kinds of Paleolithic skills from the pros there. Flintknapping, atlatl construction and use, firebuilding, etc.
I’d say I’m the man on American roots music, except that elelle kicks my ass up and down. She used to hang with Sam Phillips and RL Burnside, for God’s sake.
I don’t think there are any other Kathak dancers here. But there are plenty of dancers.
The X-Files.
Disney, especially Disneyland. I’d like to think that I’d give Eutychus a run for his money with the films.
I want to claim rabbits, or at the very least, the tiny domain of English Lop showing. Observe.
I can’t wait to graduate and get back in the show circuit.
I know quite a bit about tae kwon do, but I’m fairly certain that there’s at least one other doper (though I can’t recall who!) who’s also quite advanced in it, so I’m not going to plant my flag there.
Instead, I will say that I probably know more about the St. John’s College Great Books program than any other doper, which is in fact a reversal of the way things are in real life for me.
I won’t claim expert status, or even superior knowledge, but I have found myself entering many of the wine related threads on the board with more and more frequency over the years. I feel like I’m developing some decent general knowledge in many aspects of both viticulture and enology, as well as the service and evaluation of wine. My strong points are definitely in wine packaging, which lends itself to some general knowledge on the materials used as such; corks, bottles, screw caps, etc.
I don’t stake the topic out as ‘mine’, I just enjoy talking about it (most of the time), as it’s both a career and a hobby, and as of next week, my major. 
But it is the one topic that I can just ramble on about without having to do much research on in most aspects. There are times I do research a particular topic relating to wine, either out of personal curiosity or a question raised at work, on this board, or the lj community I manage, which only helps to increase my knowledge base.
I’ve read my fair share of books and online sources, and I’ve taken a few classes (and will be taking many more), but the best information I get definitely comes from the people I work with or meet through work functions, who truly are the masters in their areas of wine expertise. I hope to continue to learn from them.
And I’m constantly being educated by members of this board in a wealth of interesting topics.
I’m very much a generalist, and not naturally inclined to claim primacy, anyway. I tend to state things cautiously if I haven’t personally double-checked them, even in fields that I’m very comfortable with.
If I decided to stake a claim to some topic that has come up on the boards, it would probably be knife-fighting. I trained very intensely in a knife/cane style for some years, and have more practical experience than I would actually prefer. My instructors said that I was a natural with knives, although I was never more than average with canes. I won’t claim to be the top expert here (lest Danny Inosanto turn out to be a Doper), but what I do know, I’m confident about.
I also know quite a bit about the guts of cellular phone networks, especially prepaid systems, but it’s all rather boring.
As with many others in this thread, I’m generally a generalist ‘brainiac’ in real life, so all I’ve got left here are minor areas of very specific specialization.
I have pretty extensive knowledge of console RPGs and their history, but it’s started to falter with the PS2 generation. My specialty is tactical RPGs, which I do still follow avidly. I also know a lot about rhythm games, though there’s likely someone better around here somewhere.
In even more trivial matters, I’m sure my breadth of World of WarCraft knowledge is equaled here, but probably not surpassed. I’m an explorer/socializer with an excellent memory for numbers and a character of every class but mage. As for depth, while I know there are others, in my guild even, who are just as knowledgeable about maximizing dps as a combat non-daggers rogue in a raid, I doubt there are many who are markedly better.
FlyingRamenMonster, are Angband and its kin within your area of expertise? I keep dying as I pass 2500’ regardless of variant, so if you are, I’d love to know whether it’s just the normal learning curve, or something more specific that I’m not doing.
I’m another one jumping on the “well, I’m pretty good at some stuff, but others stomp my butt” bandwagon.
I’ve done a disturbing amount of research on Absinthe (especially for someone who’s never actually tried it before) so I tend to show up on those threads as they crop up. I’m sure there’s someone here who can show me what’s what.
I used to claim to know a LOT about the import “culture” in regards to import racing and tuning. I didn’t know as much about the engines and actual cars as others, but if you needed to know, say, why no2 was such a big deal in the original FAst and the Furious, or why show cars are so astoundingly ugly, I could give you the dope.
Outside of here, I’m usually regarded as somewhat of a Heinlein fanatic/expert, and I’m still pretty good in here, but Fenris is the man I can only hope to be like.
I know quite a bit about the history of Korean Martial Arts… but as NinjaChick (how you doin’, btw) said, I’m sure there’s others here that may know more than I do. Haven’t seen it in regards to General Korean Martial Arts, but I’m sure they’re here.
Andrew and Julian Lloyd Webber
Legion of Super-Heroes comics
Yeah, beer. Beer is my life, so I know a ridiculous amount of information about it. I know silenus says I’m cheating because I work at a brewery, but I got started by homebrewing so I came by a lot of this stuff before that. I am the only person at our brewery that has performed every job here, so even among my coworkers I’m a know-it-all.
Other areas I feel confident in are vegetable gardening and subjects concerning alcohol in general, but there are others here far more knowledgeable about those things. I do think that silenus, Stranger on a Train, and I could have a hell of weekend drinking binge.
Oh, and I would totally jump in on that 10/22 appreciation thread
Watch out for cmkeller.
What am I best at here?
Tolkien’s Middle-Earth. There’s a few others in my league here at SDMB, but I’m pretty good at it, and I’d go up against 99.99% of the JRRT fans out there in the rest of the world.
The practice of medicine in prison. KarlGauss and Dr_Paprika and a few others know plenty about primary care medicine, but not as much about prison as I do, so I win there!
Addictionology. I’m not an addictionist, but I know more about it than 99% of the physicians out there, and my own personal experience in the topic combined with hundreds of hours of medical education on the subject and my patient population make me pretty good at it.
I would say ginger beer, but silenus has me beat there. And he didn’t even cite it as one of his strengths! <<sob!>>
Doc, you are selling yourself short. There are several of us in a league below you on Tolkien knowledge, but your knowledge appears to be on a scholars level. I use to be part of a Tolkien Newsgroup way back in 1996 and few matched my knowledge. I would say that even your 99.99% estimate is probably low. Add a few more 9’s.
Jim
Ah, but are you Stephen Colbert good?
(just kidding, of course - I can’t compete on any level with you guys in this area, but I understand that Colbert is scary knowledgeable about JRRT and can quote whole pages of LoTR unaided…)
Get in line, bitches! 
I guess I would have to chime in loudly on hand-quilting, a subject which hasn’t come up yet.