Mr_GT said:
I have at least once or twice. Always keep that bad boy in my box just in case I need it.

I go with the former of the three. Regret and Tears and People seized with life is usually what listen to when feeling down.

i have these songs to listen...

Futago no Hoshi / Hoshi meguri no Uta (Pom Poko/Planetarian)
a xylophone only version of this song which i can't seem to find...
http://www.youtube.com/watch?v=ndgfcjxfIZU
sadness of an unending reality...
alternative with the same feel...
http://www.youtube.com/watch?v=Lc7AnTDZhzc
http://www.youtube.com/watch?v=Z_AIhEzSfW8

The Nightmare Begins
http://www.youtube.com/watch?v=vwBjCKWaO_0
sadness of past regrets that haunts you...

Say Goodbye
http://www.youtube.com/watch?v=El7r9mvcySU
Kimi no Yume
http://www.youtube.com/watch?v=y8b463yExuU
when you try to uplift a sorrow but can't contain it yourself...

Aozora
http://www.youtube.com/watch?v=U0UCdl1Dw5Q
Last Night Good Night
http://www.youtube.com/watch?v=WbH8azzyQDE
the sadness at the end of a journey...

Ihojin no Yaiba
http://www.youtube.com/watch?v=ax86j9EGd6I
Sadness that lets go of the past and not look back...

this could go on and on... i'll stop now... i just realized most of the songs i listen are sad ones...