This isn't a "song" but it is musical and makes me get all shoked up every time.
When Elphaba enters the Ozdust in Wicked and she's alone and then Galinda joins her and the music starts, ahh it just gets me. I've felt that awkward and loneliness before and it's so moving the way it is done on stage.
"You never really understand a person until you consider things from his point of view - until you climb into his skin and walk around in it."
To Kill A Mockingbird