Just a single line from a song that is sung so neat that you can’t wait to hear it when the song plays. Three come to mind for me right away,though I’m sure I’ll think of some others.
Nevermore by Queen-…and the rain stopped falling…
Gypsies,Tramps and Thieves by Cher-…Rode with us to Memphis…
The Final Cut by Pink Floyd-…Thought I oughta tear the curtain down…
Mine aren’t really lines, there are literally thousands lines I wait for in songs. But I went into this thread to post Pink Floyd, from The Trial: showing “feelings”, you can hear the scare quotes around the word.
Same with the live version of Alison by Costello:
That word is so snarlilicious, it’s lovely.
Like Ludovic, I have thousands. But the one I anticipate the most these days is Brandi Carlile’s delivery of “all of these lines across my face” at 2:53 in “The Story.” Without the pathos of her vocalization of that one line, the rest of the song is sort of trite and unmemorable. The way she sings that one line fucking makes that song.
Tori Amos has some good moments like that in many songs, as do Bjork and PJ Harvey. And Sleater-Kinney. Every single time I listen to “Jumpers,” a chill runs up my spine when Corin Tucker wails “lonely as a cloud.”
Sublime - I swear sometimes you’re taking me for granted.
Heart - “Wait for an Answer.”
There’s one singing of the refrain “Where are you, how are you, I wait for an answer, wait for an answer” where whichever Wilson is singing really lts herself go and sounds like she’s about to lose control. Just like someone who’s obviously stressed out waiting for a phone call that never comes might be. It completely makes the song for me.
Ten years ago, when my appendix burst and I had a wee bit of delirium, one line from The Wall kept repeating in my head:
I feel
Cold as a razor blade,
Tight as a tourniquet,
Dry as a funeral drum.
Great delivery (on the original album).
I’m surprised I’m the first to mention Sufjan Stevens heart rending “Oh my god” from John Wayne Gacy Jr.. Conveys the horror and sadness of the whole mess in three words.
Wow, hello fellow Floydians! Guess I picked the right thread to stumble into this morning. 
I’ve got lots, but two came to mind immediately.
Pink Floyd, from “Two Suns in the Sunset” - Right before the climax of the song, Roger says “Oh, no” in this sighing, saddened voice. Coupled with the meaning of the rest of the song, the realness of his voice when he gets to that part just tears my heart out, throws it on the ground, and stomps it into mush.
Death Cab for Cutie, from “What Sarah Said” - The title line of the song. Up until this point, his voice sounds almost defiant, like he’s trying to be brave in the face of tragedy. By the time he gets to the word “Sarah,” his voice lilts, and you just know it’s because he’s trying not to cry. It’s like in that moment, he realizes that the nurse is, in fact, coming to talk to him, and it’s not what he wants to hear.
'Scuse me, I think I’ve got something in my eye…
Behind Blue Eyes, by The Who.
“But my dreams, they aren’t as empty
As my conscience seems to be.”
Right in the middle of the word “dreams”, Roger Daltry’s voice casually pops up about an octave, then scales back down, staying on pitch all the way. And all in a fraction of a second. Daltry makes it sound easy, but you try it!
Roxy Music, Dance Away: “All the way … is far enough.”
Ben Folds - “Come pick me up…I’ve landed.”
The little pause adds a lot.
I’ll take you where real animals are playing / Where people are real people not just playing – from The Kinks’ “Animal Farm.” I love how choppy and raucous Ray Davies’ voice is right there.
And on the flip side of feelings…
I’m so happy, I’m so happy you didn’t die – Neutral Milk Hotel’s “Three Peaches.” Jeff Mangum sings this line with such misery, it’s like a blow to the stomach. Brilliant.
I really like Freddie Mercury’s vocals–just about any Queen song.
I’ve always been a huge Doors fan, and especially love Morrison’s singing at the end of “Light My Fire”. It sends chills down my spine even after having listened to it a thousand times. Similarly for the less well known cut “My Eyes Have Seen You”, from the second LP, at the fadeout:
For classical and opera singers I especially like Dietrich Fischer Dieskau–pretty much any of the Schubert song cycles.
Holly Cole singing “I Am Calling You” starting at the 50 second mark. Hair raisingly good.
And here is the behind the scenes on how the vocal was done.
“Well so could anyone”
Kirsty MacColl’s response to MacGowan’s “I could have been someone” from Fairytale of New York. Captures the emotions of the song in one line.
Hello Earth by Kate Bush…“Hello Earth, hello Earth…” haunting and beautiful.
The first thing I thought of was not a line but a bit of background singing by Bob Harris from Zappa’s Tinseltown Rebellion album. In the song Love of My Life he begins a note and holds it for about 5 seconds, then starts going higher and higher, and comes back down with a little flourish. A great little piece of vocal work. He’s good in the rest of the song as well, but that really stands out.
I always liked the line in ABBA’s “Cassandra” that goes, “Packing your bags, being slow and thorough.”
Red Hot Chili Peppers: “Get on Top”
Complications of a Mastermind…
I just love how those words are sung so differently from the rest of the song.
The way he sings “Complication” its just… perfection in that song.
Band Aid - Do They Know It’s Christmas - “Well, tonight thank God it’s them instead of you.”
The Fixx - Red Skies at Night - The extended scream of “NIIIIIGHT” in the middle of the song