In TF2, on Well, I once manage to cap all three points, alone, without any real conflict.
In Deathrun (Garry's Mod), I somehow sneaked past the death players and ran like a madman and almost made it to the end before I died from missing a jump.
In Halo 2, I was playing a 5 player free for all and not only kicked ass, but one of my friends addmited that I was the only one who managed to kill him.
And finally, in CoD4, I decided to snipe for shits 'n giggles and found that despite my rather weak sniping skills, I was dominating the enemy team, getting a 10+ killstreak (and I consider getting an airstrike luck), and even flanking someone who tried to flank me.
Sadly, I seem to only get one crowning moment of awesome per game, then it's back to getting a handful of kills among many deaths.