During the Princes of Darkness arc, Stargirl and Billy Batson find the dying body of Alan Scott. They encounter the Shade, who is somewhat reluctant to help. Stargirl (a teenage girl with no powers outside of an energy belt and energy staff) browbeats the Shade (one of the most powerful and longest-lasting DC villains) into helping them out. He's clearly impressed.
In the same arc, Alan Scott returning to the Green Lantern name and ending the shadow threat, saving his son in the process.
Sand's heroic sacrifice to hold he Earth together.
Also, Hector Hall's finally gaining confidence in himself, making a badass entry that even Mordru has to compliment.
The second Hourman sacrifices himself in the place of the first (while the third, his son, tries to make his own sacrifice).
Nathan Heywood's second issue, in which he gains his superpowers by saving his few remaining relatives from a metal villain by stabbing him in the throat. With a broken crutch. Mid-gloat.
In the Underworld Unleashed crossover, Alan Scott's wife sold her soul for youth. He entered Hell to retrieve it, and in the process, exorcised some of the souls in the Forest of Suicide. It works like this: his old enemy Blackbriar Thorn controlled those souls, who are transformed into trees by their sin. Scott saves said souls by refusing to break out of their embrace, despite no longer having a weakness to wood, as doing so would be like tearing their arms out. The fact someone still cares about them, even in that position, is enough for the spirits to be freed.
Let's be honest. Any fight scene written by Geoff Johns, if it involves a speaking role for Hawkman, against any villain more dangerous than a mugger, should be at least considered for Crowning Moment of Awesome.
Atom Smasher ripping the Worlogog out of Extant's chest, then putting him on a crashing airplane in place of Al's mother. Notably, this is what starts his major character arc of atonement, instead of coming at the end of it.
The end of his character arc, however, had him sacrificing his life to save an entire nation from the Anthropomorphic Personification of the Wrath of God. His friends, who were on opposing sides of a fight that was happening nearby, promptly stop fighting, and then attempt Godzilla-grade defibrillation. The entire scene was so badass that even Per Degaton, one of the team's most ardent foes, had to give them their due.
As a result of some time-travel, Mr. Terrific winds up in the middle of a KKK posse. An ass-kicking ensues, until there's just one shotgun-toting thug left... then the original Mr. Terrific makes his entrance by throwing some coals on the guy, setting him on fire.