Practically everyone in "Exit Wounds" gets a crowning moment of awesome. Tosh and Ianto shooting the reaper-like figures, Gwen's rallying the troops speech, Ianto and Gwen nearly shooting John, John actually shooting Jack, Jack living through being buried alive for nearly atwo thousand years and forgiving the people who buried him, Tosh and Owen's deaths
To elaborate: Tosh gets shot in the chest. It is obvious that this is a fatal wound, and the Big Bad Gray freakin' gloats over this fact. But she applies pressure and survives for something like twenty minutes while talking Owen through his own problems at the nuclear plant, which lead to his own very visible oncoming death over which he freaks out, and then calming him down and talking him through his last minutes without ever letting on that anything is wrong on her end. Only after everyone else's situation is resolved does she allow herself to die.
Ianto tasering a guy in the forehead in Meat. "Pray they survive" indeed.
In Dead Man Walking, Owen finds himself, Tosh, and a kid named Jamie Berman in a hospital, locked in with the motherfreakin' Grim Reaper, who has killed twelve people and needs one more soul to cement its power and walk the earth forever. Suddenly he realizes how to beat it, and while Tosh is working out how to open the door, he sits Jamie down for a talk about how to beat cancer, ending with:
Owen: ... the ones who have the best chance are the ones who truly believe they can beat death. So watch and learn, Jamie Berman.
Jamie: Watch what?
Owen: Watch me. Beat. Death.
And then he shoves Jamie and Tosh through the sliding glass door and takes down the Grim Reaper hand-to-hand because there is nothing it can do to him, having died once already. Death is its one trick, and it doesn't work anymore.
Owen gets another CMoA in A Day in the Death:
Security Guard: What are you?
Owen: I'm wrong.
Security Guard:(shaking)What are you!?
Owen: I'm broken. I'm Doctor Owen Harper, and I'm having one hell of a day.
To elaborate; Owen gets caught by a security guard while walking up a flight of stairs. Noticing that the security guard is mildly freaked out by how Owen wasn't be picked up by the thermal scanners, Owen begins walking up the stairs, while explaining to the guard what happens when someone gets shot, explaining that it tears and twists through the flesh. After finishing the process of freaking out the guard using the above "I'm broken" speech, he proceeds to take the guards gun and knock him out with it.
Better still when you find out that music was actually inspired by this scene. It's based on the rhythm of the phrase "Here comes Jack in bloody great tractor!"
In Cyberwoman, Jack held off Lisa by willingly getting electrocuted twice in a row. That was analogous to sitting in an electric chair, having it turned on full, surviving, then willingly going through it again. All that bought his team maybe four seconds.
Cyberwoman also had the insanely cool track  that plays when you see her the first time. Start at 1:48
In Greeks Bearing Gifts, meek little Tosh overhears the thoughts of a man plotting to kill his ex-wife, follows him to the woman's house where she finds him menacing her with a shotgun, and slams him over the head with a golf club.
Owen as "King of the Weevils".
Jack and John kissing in "Kiss Kiss Bang Bang," the ensuing fight, the post-fight chat and the confrontation with the rest of Torchwood there. "You went to murder rehab?"