Man lots of good ones here so far! Two mentions of the new boss/old boss line as of my reading, pretty worthy.
My girlfriend says "[it's] Better to burn out than fade away" - been used in more than one song.
My favorites:
"Spaceship from another star / they ask me where all the people are / what can I tell them?...
... I tell them I'm the only one / there was a war, but I must've won." - Porcupine Tree, A Smart Kid (not very rockin', this one is deeply melancholy, but the band rocks plenty)
"The illusion is sealed / The band's all wrapped in chains
Wish their vibe was still real / Now it all sounds the same" - Self, Sophomore Jinx (a derisive missive about the record industry; lots of great lines in this one actually)
it's a whole chorus but the whole thing is just, maaannnn...
"Big bang, took and shook the world / shot down the rising sun
The end was begun; it would hit everyone / when the chain reaction was done
Big shots try to hold it back / and fools try to wish it away
The hopeful depend on a world without end / whatever the hopeless may say" - Rush, Manhattan Project (self-explanatory. This chorus has actually brought tears to my eyes a couple times.)