Danny Phantom/Heartwarming

Danny and Sam's first kiss in the Grand Finale. It had all the right conditions. When Butch Hartman finally has a long awaited pairing happen, he doesn't slouch.
Just about everything in the episode "My Brother's Keeper" is heartwarming, but the Crowning Moment of Heartwarming is Jazz giving a sisterly kiss to her brother to cheer him up. After she leaves, Danny gives off a brief smile before he ruins it with a "oh, gross" comment. Still, it was sentimental.

Danny: (to Spectra) Man, I am so tired of you dumping on me. And I am so tired of dumping on myself. Jazz never did that, even when I was mad at her. And I won't LET HER DOWN!

The final episode had a few too. Specificly, right before Danny goes off to attempt to save the world and Sam gives him the "Wes" ring back. (Which hadn't been seen since season 2.) The conversation is extremly heartwarming.

Danny: Sam... If we make it through this-
Sam: When we make it through this.
Danny: Right. When we make it through this, I have a few things I need to talk to you about.
Sam: I think I'd be willing to listen. And no matter how this thing ends, this whole ride we've been on, I wouldn't change it for the world. (Places her hands in his.) Not. One. Bit.
Danny: Me neither. I- (Sam kisses him on the cheek. Danny grabs her chin, tilts it upwards and kisses her on the lips. Cue sappy music and rotating camera.) Wow. Remind me to save the world more often.

- Don't forget their second moment at the end of the episode when they become an Official Couple:

Danny: Sam, I could never have done any of this without you. (He slips the ring on her finger. She tears up.) And I don't care what's coming next. I just hope that, whatever it is, you're there to share it with me.
Sam: I will be. I just have to warn you, I'm no pushover, you know. I still have my own way of doing things.
Danny: That's what I'm counting on.
(They kiss)

The Fright Before Christmas. When all the villains team up with Danny to take out The Ghost Writer, to make it clear that no one breaks the Christmas Truce and gets away with it. And when the villains all help repair the damage to the town so that everyone has a merry Christmas.
The Ultimate Enemy. Just when it looks like Danny is about to fail to save his family and friends from an explosion, Clockwork freezes time and rescues them. Then, he takes Danny back in time so that he can undo his mistake.

Clockwork: You've given everyone else a second chance. Why not you?

- In the same episode, when Danny admits to having peeked at the answers to the test. Lancer's smile when he shows Danny the door and tells him that he will have plenty of time to study for the make up test is wonderful. You can tell that he's truly proud, even with the behaviour he usually has. And even earlier in "Teacher of the Year" when he finally gets Danny to take an interest in his studies - even if he had to use a gimmick, it is moments like these that show that Lancer truly does take an interest in his students and want them to succeed, making him less the monster the show portrays him as for the sake of a gag most of the time.
- Heck, even Clockwork has a proud smile at Danny's actions in the end. If that's not heartwarming, I don't know what is.
From "Masters of All Time" we get this touching reunion between Danny's (not)parents:

Jack: I never stopped wanting to see you. I just couldn't face you as the thing you despise: a ghost. But I had to come back because of this. (hands over Danny's wallet photo)
Maddie: A family... with you? (tears up and hugs him) Oh Jack!

In the season 2 episode Reality Trip's ending, an exposed Danny faces his stern-looking parents, expecting a full berating for lying to them for months. What he gets is them accepting him, smiling and understanding his reasons to lie. Touched as he was, he still wiped their (and the rest of the world's) memories of his reveal.

Maddie: We love you, Danny; you.
Jack: Whether you're ghost, boy, or something in-between!

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