For me there is a song for every mood, and given how moody I am you could fill a jukebox.

When I'm feeling sorry for myself:
Everyone who pretended to like me is gone - The Walkmen

When I'm feeling reflective:
Opening (from Glassworks) - Philip Glass

When I feeling like conquering Poland:
Ride of the Valkyries - Wagner

When I'm feeling whimsical:
Fish Heads - Barnes and Barnes

I'd better stop now cuz this could go on a long time.