After finishing the entire Twilight series, he didn't want the books in his house anymore, but thought destroying them would send the wrong message. So he filmed himself hiding them all over Los Angeles, with notes inside for anyone who found them directing them to his site. Unfortunately, he has yet to receive any word if this paid off.
The Sozin's Comet liveblog—old and new fans alike turned up in droves, breaking the site and surpassing the A Very Potter Musical liveblog as the most-commented event to date.
Not technically true, for example, his liveblog of Half-Blood Prince on Buzznet received over seven thousand comments. (Compared to three thousand for Sozin's Comet)
And the record was smashed into oblivion by the liveblogs of the Lord of the Rings films.
Garnering praise from Neil Gaiman himself while reviewing American Gods.
A direct quote from Mr. Gaiman: "I enjoyed your American Gods read so much. It was like getting to look through a reader's eyes & find out what worked."
The Buffy the Vampire Slayer fans crashing the site within one minute of the pilot review being posted. Mark was quickly forced to find a new server so this wouldn't happen every single day.
The final chapter of his Breaking Dawn LB, where Bella, Edward, and Jacob get fed up with the way they're written and deliver an epic "The Reason You Suck" Speech to Stephanie Meyer. Then they're prepared to kill her as fully in keeping with the characterization she gave them, but are stopped by Renesmee, who points out that whatever Meyer made them do before, they clearly have their own free will now, and can choose to be the bigger people. So they just leave her to wallow in her own shame as she weakly apologizes.
J. August Richards Tweeting that Gunn will marry him.
His response to The Great Spuffy Meltdown of 2012, furiously laying down the law before his review of the Angel episode "Dad" and the Buffy episode "Gone."
The end of his first playthrough of Dragon Age: Origins. He killed the Archdemon on his first try, with the whole party dead except Alistair, no health poultices left, and Alistair down to a tiny amount of health by the time he made the final blow. And right at the time his hour was up!
Mark's review of the first episode of Princess Tutu got more comments than Puella Magi Madoka Magica episode 1. Let me repeat that: Princess Tutu has gotten more attention than Madoka Magica did. I think this counts as awesome for PT's small but devoted fandom.
He spends most of the video for the Friday Night Lights pilot talking about how he's never cared about football, and his high school had a crappy team anyway. But from the moment Matt steps into the quarterback spot, he becomes indistinguishable from the in-universe fans watching the game, cringing at the bad plays and cheering for the good ones.
Getting nominated for a Hugo alongside one of the very books he was currently reviewing.
His furious deconstruction of Lord Wyldon's arguments for why women shouldn't be knights in Protector of the Small.
Dealing with an unbelievably poorly translated line in Fullmetal Alchemist: Brotherhood that made Ed look like a racist. What followed was a very mature discussion about the original Japanese line and the various ways it's been translated, how some are much better than others, and how the dub translation was pretty much the worst choice they could possibly have run with.
When he announced he was doing Supernatural, he said he'd just give the first season a shot, and stop if it hadn't grabbed him given the problematic things he'd heard about the show. Then when he actually got to it, he announced that he would be doing the whole thing (with the show still ongoing and about to begin its ninth season) just to spite the people who insulted him for watching it in the first place. He finished by saying that even if he ends up hating it, it will still be fun to write about as a return to his Twilight days.
In Chapter 15 of Untold, his response to being accused of only saying he likes the book because he knows the author is reading his reviews.
And when he was very nervous about tying in detailed stories of his own life while reviewing the book, to a much greater degree than ever before, Gaiman replied that it was the perfect way to review it.
His reaction to the Mighty Whitey aspects of Daughter of the Lioness, showing that he's not going to let this kind of thing slide, even from one of his favorite authors who is also a commenter on the site. And once again, the other commenters provide a completely mature and thoughtful debate on the subject, with none of the childishness you'll see just about anywhere else on the Internet where these subjects are discussed.
Providing impromptu accompaniment to the first instance of "Carry On, Wayward Son" in Supernatural.
For someone who is so often blindsided by plot twists, he figured out the America the Beautiful clues in The Westing Game very quickly.
And the theme naming, though he didn't guess what it meant.
Taking eight fans to see the Veronica Mars movie on opening night, for free. And he said any other fans in the area were welcome to come too.
He again shows he's not going to let problematic stuff go even in works he loves when he takes Veronica Mars to task more and more for the Straw Feminists in season 3.
In an inversion of the Supernatural reaction above, he received so much hassling by bronies to drop everything he was doing and cover My Little Pony: Friendship Is Magic immediately, along with big doses of racism, sexism, and spoilers, that he took the show off his list entirely and now refuses to ever watch it, since it would be impossible to separate the show itself from his experience with the fans.
While watching The Middleman he's exactly in tune with Wendy Watson, to a kind of scary level. The highlight is when they say "Sweet" at the exact same time when the Middleman brings up ghosts.