Awesome / Harry Potter and the Philosopher's Stone
Hagrid righteously terrorizing the Dursleys after he finds out that they've been lying to Harry for over a decade is one of the most satisfying things ever after the continuous abuse Harry's been put through.
Hagrid bending Vernon's gun "into a knot as if it had been made of rubber" and throwing it out of his reach.
Three first-year students take on a fully-grown mountain troll and not only survive, but defeat the troll.
Immediately afterward, Hermione saves the boys from being punished by not only lying to the teachers but also willingly making herself look like a rule breaker, telling them that she thought she could handle the troll herself and went looking for it to defeat it and the boys came in to save her (in reality, the troll found her by chance and the boys broke the rules to rescue her). Considering the fact that she was not only at these boys' throats for much of the book but considers being punished for rule breaking to be worse than dying, this was a pretty gutsy move on her part.
Later, those same three first-year wizards take on an obstacle course designed by their teachers and beat it.
Hermione saving Harry's ass by setting Snape's robes on fire. In truth, Hermione saved him by accidentally knocking over Quirrell on the way, who was enchanting Harry's broom. Snape was chanting the counterspell.
Harry catching the Snitch with his mouth.
Dumbledore's scene in the hospital wing with Harry.
Neville — the class klutz — standing up to his friends to protect the honor of his House. His only friends. It gets more awesome when you realize that Lupin and even Dumbledore, in similar situations, didn't have the courage to do what Neville does in his first year.And, this act ends up giving Gryffindor enough House Points to win the House Cup.
This turns out to be Foreshadowing of the final book, where he openly defies Voldemort himself!
Neville also jumping into the fray when Ron fought Malfoy. Neville took on the two physically strongest first years, at the same time and he held his own against the two long enough for Ron to give Malfoy a black eye.
The poke of death!
Lily's sacrifice. Voldemort wasn't even going to kill her in the first place, but she offered herself instead of her son, got killed first, and essentially defeated Voldemort by protecting her son.
"I think I can tell the wrong sort for myself, thanks."
Harry frightening Peeves away by impersonating the Bloody Baron.
Dust-Voldemort trying to kill Harry. Scary as hell? Yes. Completely awesome? Hell yes!
When Quirrell was warning about the troll and fainting and the students begin to panic and run amok, Dumbledore stopped them simply by shouting "SIIIIIIIILENCE!!!". Before calmly instructing the teachers and prefects on how to deal with the situation. Unlike the later example, he didn't even need a wand to make his voice heard.
Dumbledore quiets the hall down differently in the book. While he does use his wand, he instead summons purple firecrackers with it.
In the book, Ron winning the chess game will trying to avoid three specific pieces was epic enough. In the movie, however, he loses a pawn beforehand just to check what'd happen, giving him an even greater disadvantage, but he still wins.
A meta one for director Chris Columbus: because of his negative experience working with Macaulay Culkin's father Kit on the Home Alone movies, he interviewed not just the kid actors but their PARENTS and immediately eliminated all those who came off as stage parents. The reason the Golden Trio gave such great performances over the years and grew into such well-adjusted adults? Columbus had enough foresight to make sure their performances came from the right place. Good on him.