First off, 8) to that sig quote. Even if it's accidental, TMBG r00lz #1 d0000d!!!!!!!1
Okay, these songs are legion... I used to make "diary" mix tapes when I was in high school, with things like this.
Presently, as mentioned in the favorites thread, "Do Your Best and Don't Worry" by Morrissey:
<i>Compare the best of their days
With the worst of your days
You won't win
With your standards so high and your spirits so low
At least remember:
This is you on a bad day, you on a pale day
Just do your best and don't worry, oh
The way you hang yourself is oh, so unfair...</i>
*sigh!*
Also by Moz, "Disappointed" - which is more of a scattershot song, so it's hard to pull out just one relevant line. It's upbeat-ly pessimistic, if such a thing can be imagined, with a sort of sarcastic sense of humor that I relate to. ("Young girl, one day you will be old... but the thing is, I love you now.")
U2's "Walk On" was very soothing to me during a chaotic time in my life, early this year. So that, too.
Gladys Knight and the Pips' "Midnight Train to Georgia". Because I had something like this happen to me, except I didn't go. :/ I'd heard it before, but re-hearing it recently I realized what a sweet song it really is.
REM, "Why Not Smile". Pretty clear, there. Though to me it recalls the idea of an idealized friendship, something very calming to think about sometimes. Great tune.
The Smiths, "Bigmouth Strikes Again", which has been my evil theme song ever since I first heard it - and would have been earlier, if I'd heard of it earlier. (Placebo did a decent although less vicious cover of it, if you're allergic to anything made before 1990. ;P) It's basically the theme song of self-deprecation.
Anyhow, it goes on and on and on.

Which is what's great about music, I think, how everyone relates to it differently.