The friendship that develops between Liz Lemon and Jack Donaghy provides a number of these. One of the best is in the second season finale, when Jack, in D.C. working for the Bush administration, is left a number of voicemails by Lemon stressing out over a pregnancy scare. After he listens to them, he shows up at her door, tells her, "I'm sorry you had to go through this alone," and offers to help her begin the adoption process. All this from two characters who kind of hated each other at first sight.
A more recent one was the season four Valentine's Day episode that had Liz scheduling a root canal for V-Day, because she didn't need a man in her life. Except the dentist's office requires someone to drive Liz home since she's going to be on anesthesia (and she does exhibit some fun side effects, including cuddling the office plants and mistaking the dental assistants for her three ex-boyfriends). They call her emergency contact - Jack, who has been attempting to romance a political pundit who won't take him seriously - and he immediately drops everything to come pick Liz up and take her home.
There is something about this exchange that this troper has always liked, especially between Jack and Nancy.
Jack: "I'll wait, not forever."
The scene where Jack, who is trying to prove to Kenneth that no one is really moral when tested, gets a bunch of people to rig the elevator to break down and play a trick on him, saying that there's only enough oxygen in the elevator for eight people to survive and since there's nine in the elevator, one person has to die (and mentions there's a gun conveniently located in the phonebox). The fact that Kenneth is gullible enough to believe him is a Crowning Moment of Funny. The fact that he doesn't hesitate for a second before grabbing the gun and trying to shoot himself in the head to save Jack and the others is the Crowning Moment of Heartwarming. Jack, it should be noted, is completely shaken by this display.
Kenneth's naivete and pollyanna personality are often played for laughs, but there are times when his idealism and good nature becomes genuinely heartwarming.
Kenneth [speaking about a rival he's known for a few days]: He's my best friend! Tied with everyone else I've ever met!"
Jack and Liz are renegotiating contracts, and Jack realizes that he loses out on the deal because he cares too much about Liz. He uses this to his advantage to prove he could still beat her, but signs the favorable contract anyway.
Jack [offhand]: I still want you to have everything.
Jack Donaghy finally gets his job back at the beginning of Season 3, and Liz is on her way out the door of his office when she stops and looks behind. When Jack asks her what's wrong, she replies "nothing, I just like seeing you in there."
Liz ends up showing sincere concern for and friendship to Jack as the show goes along, and some moments can make one feel a little fuzzy inside - though it's not long before the snark snaps you out of it.
Liz deciding in "It's Never Too Late for Now" that the enormous office conspiracy to get Liz a one-night stand means everyone knows her extremely well and really cares about her happiness.
The Season 5 Christmas Episode, especially at the end when Jack deliberately annoys his parents just to have them yell at him - like a normal family. His contented smile says it all.
Followed by a genuinely sweet sequence in which Paul and Jenna sing a Christmas carol while Liz returns to her family.
The Season 4 Christmas Episode when Danny deliberately sings off-key just to please Jenna during their duet.
Jack's reaction to his phone messages from Liz during the Season 2 finale and then traveling all the way from Washington D.C. to her apartment in New York in the middle of the night after realizing she needed a friend to talk with.
What does Don Geiss tell his employees to do in the event of a financial meltdown in "Larry King"? "We've all worked hard, but now it's over. There's only one thing for you to do... go to your loved ones. Hold them close; because, in the end, and if you're watching this, it is the end, love is all that matters."
At the end of Season 6, Liz tells Jack (usually a ceaseless fountain of unsolicited advice) that she's finally ready to have a child of her own, but Jack, humbled by the failure of his second marriage, does not feel qualified to mentor her, instead just telling her that she'll be a great mother. But Liz asks for his advice anyway, in an honest display of admiration and friendship, and Jack, in an equal display of friendship, obliges. Awww....
In the season four episode "Sun Tea" there's two CMO Hs. The first one comes from Tracey and Jacks expericences while waiting for their vesectomies. Jack bonds with Tracey's son, who loves his dad so much that he's basing a project for school on him. Tracey's expericence is that he finds he wants a baby girl before he gets the operation because he genuinely wants another child. This leads to Jack stopping the operation on Tracey. The second of CMOH is Doctor Spaceman's reactions to this. He volunterily stops Tracey's procedure because Jack asked him too and his explanation to why they can't eat a huge meal before surgery is not because of throwing up in their sleep but because he's making them both a huge breakfast after. He almost levels Kenneth in kindness (and oddball-ness)and this episode really solidifies this.
After hearing about how much Kenneth loves NBC and what it means to him Jack makes Kenneth the new CEO of NBC.
In the finale, Jack loves Liz . . . like their Anglo-Saxon forebears would have loved each other:
Jack: Lemon, there is a word, a once special word thatís been tragically co-opted by the romance industrial complex, and I would hate to use it here and have you think that I am suggesting any type of romantic sentiment, let alone an invitation to scale bone mountain. Itís a word that comes to us by way of the old high German "luba" from the Latin "lubera" meaning "to be pleasing." So Iím going to use this word to describe how I feel about you in the way that our Anglo-Saxon forefathers would have used it in reference to say "hot bowl of bear meat" or "your enemy's skull split.
Liz: I love you too, Jack.
Also in the finale, Tracy spends almost the whole episode looking for Kenneth/trying to get in touch with him which is made 100x more difficult since Kenneth is president of NBC. It seems like Tracy is just being his usual needy self. But when he finally finds him, it's so that Tracy can release Kenneth from his promise of always being there for Tracy, knowing that otherwise, Kenneth might spend more time and effort on Tracy rather than on more important things.
However, the entire reason Tracy suffers severe abandonment issues gets closure, as his father returns from getting cigarettes. It's one of the only times Tracy is ever unconditionally happy.
The final scene; we zoom out of a snow globe of 30 Rock and see Kenneth discussing the idea of a 30 Rock TV show with a "Miss Lemon". It seems like a send up of the controversial ending of St. Elsewhere, in which it was All Just a Dream. But then we see flying cars going past Kenneth's window, and realize it is the future; the "Miss Lemon" is actually Liz's descendant, basing a show on the stories her great grandmother told her. She tells Kenneth this and he (looking no older, by the way) says "I know... and I love it!"