Mr. Feeney performing a dramatic monologue from Hamlet after Cory doubts that there's any appeal in Shakespeare's work to people his age. He knocks it out of the park.
Mr. Feeney's speech to the class in "Quiz Show", while Anvilicious, is quite awesome:
Mr. Feeney: Champions of what, Mr. Matthews? Of a generation whose verbal and mathmatical skills have sunk so low, when you have the highest level of technology at your fingertips? Gutenberg's generation thirsted for a new book every six months. Your generation gets a new webpage every six seconds. And how do you use this technology? To beat King Koopa. And save the princess. Shame on you. You deserve what you get.
And then the bell rings. As the kids go to leave, he flips, tells them to "sit back down!", and solemnly declares, "For the first time, I'm walking out on you."
And Then There Was Shawn is a beautiful send up to the slasher genre and Scream.
Near the end of Chick Like Me, S:4-E:15, after being constantly touched and felt up by Gary, "Veronica" (actually Shawn) is accused of liking girls instead of boys because she won't let him touch her. She growls, "As a matter of fact, I do," then repeats it before she punches him off his feet and comments, "For every girl I've ever known" when asked why she punched him. Then she leaves with Topanga and Cory (Cora) to go write an article about the experience, therefore spreading the word about Gary's grabby hands to the whole school.
Will Friedle performing Shakespeare quite well, ending it as only Eric could with "Prepare to die, Jedi Master!"
"No, listen, you see! A judgment I made a long time ago is that Shawn Hunter is the best friend that my son ever had. And I will kill to protect Shawn Hunter from people like you."
Eric's speech to Dean Bolander about how he needs to go to Penbrook University, saying that he wants to live up to the potential everyone says he has & that if the college doesn't let him do that, then it's the one not living up to it's potential. Especially when it turns out that it convinced her to grant him admission to the school. The studio audience outright cheered at that point.
Really, the entire arc Eric goes through in Seasons 3 & 4 - He doesn't put the work in during in High School & finds himself rushing to get his grades high enough to get accepted into college, only to fail for that exact reason. Come Season 4, and after struggling with adjusting to life after high school, he then makes the effort to get into college & that speech is the culmination of the arc, and the pay-off to Eric being crushed when he reads his rejection letter the prior season.
There is one little thing that makes it better, and it's that at the end of season 3 Eric is rejected from a "safety school" (a college where almost anyone gets in and little is required of the students) only to get into the far more prestigious Pennbrook in season 4.
Eric hijacking an extremely glitzy wedding (said to be the social event of the year) from a disposable diaper mogul for Cory and Topanga.
When Griffin arrives at John Adams High, he proceeds to immediately get dates with several of the hottest girls in school within minutes. Later, after rebuffing Frankie & Joey's offer of being his lackies as he has no need for them, he's confronted by several angry members of the football team. After Griffin's challenged to step outside, Frankie & Joey step up and say they would love to go outside & talk. When the jock states it's between him & Griffin, Frankie gets the absolutely badass line "No. We're between you & him."
Cory, Topanga and Shawn go to the school to stop vandals from trashing the school. They assume Shawn's there to join them. When they hand him the spray paint, Shawn knocks it out of the guy's hand, quotes the First Amendment (he accidentally read the chapter), and credits Feeny as the reason he's not with the rest of them.
Eric teaching a group of immigrants and earning Feeny's respect despite disobeying himearlier that episode. Personal favourite Eric moment