This.
http://www.youtube.com/watch?v=hsCriuU_Uqk
The story?
An accident happened, and I ended up watching a friend of mine die. It's hard when something like that happens because you begin to wonder if you could have saved them. I drove home in silence. I was living alone at the time so there was no one to talk to, though I don't think I would have wanted to anyway. I went online to distract myself and saw that a website had been made for the upcoming Advent Children movie. I went to it and heard that song, set on repeat. I remember laying face-up on my bed,staring at the ceiling, listening to it over and over. It comforted me.
When I hear it, it takes me back, but it is always more comforting than sad. I later got a translation of the lyrics, which I found to be profound given the associations I draw with the song.
...
Honorable mention to Reuben Kee's "Ascension to Cosmo Canyon".