"The Song of Purple Summer", as all cast members dead and alive assemble on stage to sing a song of hope, love and the world going on.
Especially unbelievably heartwarming after Moritz and Wendla's ghosts will Melchior to live on after their deaths, and stop him from committing suicide.
Melchior and Moritz's hug when Moritz sneaks into the Principal's office and finds out that he has passed the midterm exams. The two hug at the end of the scene, but the two actors must remain hugging in the background (not lit) as Fraulein Knuppeldick and Herr Knockenbruch talk about these goings on in the foreground, which makes it rather funny yet must be unbelievably awkward for the actors.
Also, the line before they hug which Moritz says in his joy is "Truly, heaven must feel like this!", which John Gallagher Jr (who originally played Moritz) incorporated as the last line of his speech when accepting the Tony Award for Best Performance by a Featured Actor in a Musical.
The part of the hayloft scene when Wendla realizes that she wants to go through with what they are about to do, and manages to kiss Melchior back.
Wendla: Melchi, no—it's just—it's...
Melchior: What? Sinful?
Wendla: No. I don't know!
Melchior: Then why? Because it's good? Because it makes us FEEL something?
Wendla: (Exasperated) I don't know! (Wendla returns his kiss fully)
"Touch Me" is an Intercourse with You song that manages to be heartwarming at the same time, because it's so emotional and gorgeous compared to other similar songs.