Harry animates Sue the T-Rex, the one from the actual museum in Chicago, to serve as his steed as he rides into battle against an army of necromancers and zombies. Did I mention it was controlled by not only his magic, but his sidekick's one-man polka suit?
By the way, in the Dresdenverse, the older a corpse is, the stronger it is when animated as a zombie, but it's also commensurately harder to reanimate. Nonhuman zombies, preferred by Harry because they're not Forbidden Magic, are weaker, but more difficult to create and control. The walking corpses summoned by the Big Bad in Dead Beat range from less than a year to maybe a few hundred years old. Sue is roughly sixty-five million years dead, and was famous several years back for being one of extremely few complete skeletons ever found.
Bigger bonus? The Dresden Pen and Paper RPG includes rules for doing this yourself. The stats for Sue in particular as an opponent basically translate to "You lose."
Bonus: Harry summons the Lord of the Wild Hunt, a fae on par with the Fae Queens themselves, and binds him so that the competing armies of necromancers can't use him. Then, after the big ending fight, the Lord spares Harry because even he thinks reanimating Sue was awesome.
Hell, summoning the Erlking is a moment of awesome on its own. Harry summons and tries to bind one of the most powerful Fair Folk in existence. This will give said Fair Folk a personal grudge against Harry, which means the Lord will probably kill him within a day or two even if bound long enough for Harry's purposes. (Remember back in Storm Front when Harry comments in the narration that he'd never try to summon and trap Santa Claus in a magic circle because "nobody has stones that big"? Various bits of Word of God, plus the eventual appearance of "Kringle" in Cold Days, indicate that summoning the Erlking is comparable to that.)
The Awesomeness that is Zombie-Sue is recognized in the book when he does it: Harry doesn't make a big deal about it, but Luccio, commander of the Wardens who should by all rights be appalled at the necromancy (even if it isn't technically illegal), can't quite get over her feeling of stunned disbelief. And Warden Ramirez immediately thinks it's the coolest thing ever.
Not least because the first moment they see her, it's because Sue just bounded completely over their heads to stomp the hood of a car that was about to run them over, driving its engine block about a foot down into the pavement.
The Awesomeness is recognized in more then the one book. More then one occasion later in the series it's mentioned that characters are wary of Dresden. It's never specified which of Harry's many accomplishments caused others to fear him(and he has quite a few), but when Harry lists the many moment of awesome that could lead to some being afraid of him he always seems to come back to Sue as the top of the list!
Remember that ghoul? The unstoppable ninja flesh-eater who nearly killed Harry in the alleyway?
Sue ate him. Snap. Gulp. No more ghoul.
Harry telling Mavra, in no uncertain terms, that if she ever tries to get to him through Murphy again, he will take her down with extreme prejudice is worth a mention, too.
Harry: "I've got a fallen angel tripping all over herself to give me more power. Queen Mab has asked me to take the mantle of Winter Knight twice now. I've read Kemmler's book. I know how the Darkhallow works. And I know how to turn necromancy against the Black Court. So once again, let me be perfectly clear. If anything happens to Murphy and I even think you had a hand in it, fuck right and wrong. If you touch her, I'm declaring war on you. Personally. I'm picking up every weapon I can get. And I'm using them to kill you. Horribly. Do you understand me?"
The best part was that she nodded and moved to leave. Harry stops her, snarling. "Say it!". Marsters used a nearly insane with rage tone that just sends shivers down a reader's spine.
Oh, and speaking of the sidekick's one-man polka suit... Waldo Butters is a 5-foot-nothing, 98-pound weakling nebbishy coroner. He is not a trained cop like Murphy, he doesn't have a connection to the higher powers like the Knights, he doesn't even have the ability to turn into a wolf like the Alphas. But, after a very crappy day involving zombies, necromancers, and psychopaths who either want what he knows or want him dead, he finds the fortitude to save Harry from a knife wielding psycho in a fist fight. He didn't do a hell of a lot of fighting, but he always put himself between the guy with the knife and his friend.
And never forget: POLKA WILL NEVER DIE!
Also don't forget that said getting between the guy with the knife and his friend involved attacking the psycho with his teeth.
Butters skittered away from the knife, eyes wide with terror.
But he skittered directly between Cassius and me.
And held his ground.
A small thing, but Butters also manages to keep his cool enough that, during the final battle, he actually manages to use the knowledge Harry has taught him to create a warding circle to protect himself from the undead, while lethal and deadly specters are closing in on him from all sides.
Morgan, after thinking Harry turned on them and killed the Warden commander when he proves himself willing to go through said reanimated T-Rex to bring Harry to justice. He's probably able, too; see Proven Guilty.
Harry's reaction to this is also awesome; within the space of a second or two, he calculates all the possible outcomes of the confrontation, and realises that the only way the good guys would have a chance of preventing the Kemmlerites' victory is a Thanatos Gambit. He then simply prepares his death curse and waits for his end. Good thing Ramirez interferes.
Thomas, riding with the Wild Hunt.
And Bob, after the Big Bad necromancer puts him down, possesses Sue to come to Harry's rescue.
The Senior council was being chased through the Nevernever by Red Court vamps, demons, and at least one Eldritch Abomination. The Merlin held off the entire freaking Red Court with an impromptu ward.
"I guess you don't get to be Merlin of the White Council by collecting bottle caps."
Luccio shows Harry why she's the captain of the Wardens by destroying thirty undead in under five seconds,the rest of the Wardens handle the rest and not one child is harmed in the process.
Harry telling off Kumori for her arrogance about ending death.
After six books of taking crap from the Council, Harry finally gets to tell them exactly what he thinks of them and why he treats them with such disdain.