What's the saddest song?

I'm a big fan of sad/depressing/melancholy music and I'm looking for the saddest song/piece of music that's been made.
Currently I think the winner is 'Exit Music (for a film)' by Radiohead.
Pretty close are Mad World from Donny Darko, Adagio for strings by Samuel Barber (Platoon music) and Leaving Hope by Nine Inch Nails.
What prompted me to post was I recently discovered this artist, http://www.myspace.com/katewalsh which reminded me this 'quest' has led me to some really good music.
Anyone think they've found a song more depressing than Exit Music?
Currently I think the winner is 'Exit Music (for a film)' by Radiohead.
Pretty close are Mad World from Donny Darko, Adagio for strings by Samuel Barber (Platoon music) and Leaving Hope by Nine Inch Nails.
What prompted me to post was I recently discovered this artist, http://www.myspace.com/katewalsh which reminded me this 'quest' has led me to some really good music.
Anyone think they've found a song more depressing than Exit Music?