Music Thread: Songs to hear at least once before you die

[MEbenhoe]

Recently I discovered the music of Jeff Buckley. Strangely enough after reading up about him, I realized I remember hearing about him drowning when I was younger, but having no clue who he was. I found myself discussing with a friend how cool it is to discover music like that that is 10-15 years old, but that somehow you never heard before and to just go wow that is a beautiful piece of music, how did I miss that?

This sparked this idea in my head, what are songs that you feel someone would be missing out if they didn't hear that song at least once in their lifetime. This is different than a favorite songs list in my mind, as for example Everlong by the Foo Fighters is one of my all-time favorite songs, but I would not place it on this list. Basically just songs that regardless of genre, likes or dislikes, or whatever else can be widely appreciated simply as a beautiful piece of music. I don't know if this makes sense, but here's a few to get the list started (obviously will end up more slanted towards my generation).

Jeff Buckley - Hallelujah (song that inspired this thread)
Johnny Cash - Hurt
Neutral Milk Hotel - King of Carrot Flowers Part 1
R.E.M. - E-Bow the Letter
The Shins - New Slang
The Smashing Pumpkins - Disarm

So what else am I possibly missing out on?