Coach laying down the law when Voodoo decides to be his own coach.
When Coach finds out that Julie let him believe Tim was taking advantage of her while she was drunk, rather than helping her and protecting her from a creep, he responds "Damn, Julie. Damn." Kind of a Moment of Awesome for Kyle Chandler as well, since according to episode commentary there was originally a long speech planned, and Chandler adlibbed that line instead.
Coach chasing Julie's lecherous TA off his property.
Matt Saracen leading the team back to the brink of victory in the season 3 finale after JD McCoy implodes.
Buddy Garrity telling the Panther boosters to go to hell when one of them calls Tami a "bitch" and then calling Joe McCoy a cancer who has ruined the program and the town.
Matt in the first episode, stepping in for the paralyzed Jason with a beautiful pass to win the game.
In "Thanksgiving" Landry kicking the winning field goal, and Coach's pep talk before it, ruining JD McCoy and the Panthers's playoff dreams.
Every single season finale has one relating to football.
"Black Eyes and Broken Hearts", wherein Tim Riggins demonstrates that you can only be a racist bully for so long before he'll have to put you down.
Tyra chasing her mother's boyfriend out of the house (after he hits her) with a fire poker, and then standing her ground and daring him to hit her when he gets the fire poker off her. Made even better by the fact that she doesn't look remotely scared of him, just furious.