Pretty much anything by Simon and Garfunkel. Listened a lot in college, those albums got me through years of late-night physics homework. I guess at age 20, a little melancholy spices up life. But now, after buying a complete set of their albums on CD, I find that I can't listen to them at all without them getting me waaaay down. Not even counting how one side of the family settled on Bridge over Troubled Waters as a perennial funeral song.
But then, Puff, the Magic Dragon has always given me intimations of mortality.