The Agony Booth's Mr. Mendo does this in his reviews, but really shines when dealing with hostile commentors. For example, after someone took issue with him trying to prove that Forrest Gump was a bad movie, he responded:
Mr. Mendo: You're right, I should never have the courage of my own convictions. It's bad manners, you know...
The Angry Video Game Nerd is famous for the sarcastic remarks he use when he's reviewing bad games. Half the fun of the show is his very deadpan personality.
BikdipOnABus can be this sometimes, especially to stupid commentors.
In his podcasts and website, skeptic Brian Dunning actively uses deadpan snarking in his articles.
I have no idea whether a single atom of magnesium restores sex hormones, whatever that means, but if so that's one hell of an atom. If you want magnesium, take a vitamin pill. If you want oxygen, take a breath. If you want sex hormones, get a girlfriend. -Wheatgrass article
Oancitizen. His field of expertise (arthouse movies) provide ample material.
Los Hermanos, a member of the titular Global Guardians superhero team, is probably the most notable heroic example in the Global Guardians PBEM Universe. The most notable villainous example is likely The Evil Mastermind (a hyper-intelligent, nine-year-old Gadgeteer Genius and leader of Evil Mensa). When the two of them face off, it's a veritable hurricane of snarkiness:
The Evil Mastermind: "Now that you're in my clutches, hero, I'll..."
Los Hermanos: "... bore me to death with the gloating and the grand-standing? You're like a villain out of an old-style movie serial."
The Evil Mastermind: "Oh dear, your use of a reference to a form of entertainment that hasn't been produced in sixty years has destroyed my self-image. What will I do now?"
Los Hermanos: "Go back home and finish your homework?"
The Evil Mastermind: "Ooh! And now comes the crack about my age! You know, that's almost but not quite completely ineffective! But please, do keep trying. It's always important for people to think they're accomplishing something..."
Alucard: Oh, I'm sorry, I like to dirty talk when someone's sucking my dick.
Luke: Perhaps I should just skip to my point. My name is Luke Valentine.
Alucard: And I'm Carmen Sandiego! Guess where I am!
Luke: I'm trying to have a serious conversation with you here.
Alucard: Oh, so am I. And I'm failing... and I'm sorry for that. It's just that I'm so agitated, because this blond little shit strolled into my room, destroyed my 70" plasma TV, and is trying to impress me like I'm his alcoholic father!
(Luke and Alucard point their guns directly at each other's head)
Alucard: Be a sport and grab daddy another beer, would you?
Andi: So, want me to write a computer program for you longhand? Best to give me a topic — I couldn't think of one. I'm not entirely sure what people write computer programs about. The book suggests it should just output 'hello, world,' but I’m not one to make that kind of unambiguous welcome to a planet I've barely even seen before.
Alex: (after his house had been broken into) Hey Jay, you forgot your flashlight.
Curt, from Mirror Fall definitely counts. In response to being teleported with Stef into the infirmary where the resident twin doctors are engaging in some, ah, 'creative healing' he covers Stef's eyes and says when she protests, "‘Newbie, don’t ask unless you want to see a very explicit answer to the question “what’s up doc?
Almost all of the characters of Red vs. Blue get in on the fun, but a few get surpassing mention:
Church. This is his nice mode. From here, it escalates to acidic rage. He does hang on to the snark, delivering some of the series's best lines.
[In an answering-machine sketch] "THERE IS NO ELEVEN YOU FUCKING WHORE"
The Red team passes this ball around - they'll take turns suggesting stupid things, and then the others will drop the snark-hammer on the idea.
Agent Washington. What happens when you take an idealistic soldier and mind-rape with your own suicide-inducing memories as his teammates kill each other and destroy his home in the fight? What happens when you dangle a way out of it all just beyond his newfound friends? Apparently you get a bitter, vengeful, creepily-clever snarker.
Danny Brady in Shadow Unit often fills this role, and so does Daphne Worth from time to time—usually when she's trying to outdo Brady.
The Surf Ninjas review. A whole episode of snarkiness. WOW.
The Cinema Snob has such a great voice for it, too. Case in point from his Island of Death review, when he sees a character get brutally slaughtered with a knife and a gun, then another character says that they don't know how he died.
Snob: If only the stab wounds and bullet holes had given us more clues!
In the fourth anniversary movie, To Boldly Flee, the award for this goes to Sad Panda, who achieves a sort of stoic nirvana in which his face does not budge an inch and he does not utter a single non-sarcastic line.
Peristrixalo from The Wanderers Library. “Just once, I would like to meet something beautiful that tries to kill me, but I suspect that's asking far too much.”
The Freewebs RPG Warriors The Final Cry has Ivypaw, a ShadowClan-born she-cat who ran away to ThunderClan to escape her abusive mother. She can be quite the snarker at times, though is mostly friendly about it.
In Worm, the protagonist's supervillain team, the Undersiders, has three: Tattletale, Regent, and Imp. Perhaps not coincidentally, each of them have powers that are well-suited to screwing with people's heads.
The reporters for Yahoo's Odd News, especially Greg Proops, make humorous comments on everything they report about.
Yugioh The Abridged Series is full of delicious snarkiness, especially Kaiba, Yami Yugi and Bakura, though everyone gets their snarky moments
Ben Croshaw very rarely feels the need to be deadpan—his humor's most often very blatant. Every so often, though...
This guy is pretty sarcastic to his father while he's making himself ready to hang himself with his tie. Then again, that's pretty understandable after reading My Immortal.
Snark has a certain cathartic or ego-stroking value for many people especially if it seems to go over the heads of their targets. For this reason and also because of the GIFT, many netizens will snark as much as possible at anything they come across. Attempts are often made to veil genuine anger at someone else's snark with one's own cutting wit, usually with cringe-worthy results.
Admit it. We Tropers are a snarky bunch.
People on Facebook either ignore utterly pointless or vague statuses, or deliberately make fun of them. There really is no in-between.
Many YouTube commenters will show up on a video that does not interest them at all just to snark at the fans (or the fans' comments).