This is based on opinion. Please don't list it on a work's trope example list.
Tear Jerker / Jonathan Coulton
"I'm Your Moon," described elsewhere on this very Wiki as "the most touching song about astronomical taxonomy ever written." Yes, it's quite literally about Charon trying to cheer Pluto up after being demoted to dwarf planet. But really, it's hard NOT tear up at the gentle sweetness of it. "From out here, it's the rest of the world that looks so small..."
In his series of blog posts about the fifth-year anniversary of his Thing a Week project, he noted how a song he'd only given a little bit of thought to had exploded beyond its boundaries. Although he wrote the song about Pluto and Charon, the ways in which people had been using it—as a song at their weddings, as a lullaby for their children—had made it into so much more. And he thinks that's awesome. So he's acknowledged its power himself, and just knowing how much the song has struck a chord with people is tear jerker in itself!
He is better known for awesomely geeky songs, but When You Go is a very simple song about love and loss. Set to a memorial video for a fan's pet hedgehog, it's so sad and sweet.
"When You Go" can really affect those who have either lost loved ones, or have loved ones that are on the brink of death.
Then there's "Big Bad World One." What's this one about? Simply about giving up entirely under the weight of every bad thing the world can do to you.
"I Crush Everything". "This one's about a self-loathing giant squid." Sounds hilarious, don't it? Wrong.
"You should know How great things were before you Even so, they're better still today I can't think of who I was before You ruined everything In the nicest way."
Even more so when you know that Jonathan Coulton wrote this as a love song to his daughter, and when he plays it at concerts, it's always preceded by an introduction about becoming a first-time parent.
"Space Doggity." Ignore the funny title (It's a homage to David Bowie's "Space Oddity", obviously) this song is so depressing it's unbelievable. It's about Laika, the dog the Russians put in space and her last moments - and it's hard not to break down in tears. It hurts because it loves. What makes it worse is the third to last verse, where the scientists back home discuss the failure of the mission.
"It's a shame There is always something that gets compromised."
Although, it may be more heartbreaking in the verses sung from Laika's point of view, alone and dying in space. "I don't think I want to be a good dog anymore." *sniffle*
"Womb With A View," a very gentle, almost bittersweet song about two "artificial wombmates" culminating in one being born into the world and wondering if the bond they've shared will last.
"Maybe when we get outside, we'll both still remember Maybe someday we will meet on the street, and I'll know it's you..."
Blue Sunny Day. A lovelorn, death-seeking vampire experiences a brief, shining moment of happiness before daylight brings him down. Plenty of Lyrical Dissonance between the jaunty, bouncy music and the subject matter.