Any song by the Spice Girls, duh!
Actually, a few songs tend to reflect me - depending on my mood.
Wired Claire: Seven Boom Melody by Freezepop
Nerdy Claire: The Geeks Get the Girls by American Hi-Fi
Relaxed Claire: The Bard's Song by Blind Guardian
Dancey Dance Claire: Believe by Cher
Excited Claire: The Suffering by Coheed and Cambria
Lovey Dovey Claire: Heaven by DJ Sammy
Nervous Claire: May It Be by Enya
Irish Pride Claire: Drunken Lullabies by Flogging Molly
Callow Claire: Sex ED Rocks! by I Set My Friends on Fire (feat. Smosh)
Upset Claire: Hurt by Johnny Cash
Totally Happy Claire: The Joker by Steve Miller Band
Super Confident Claire: Victory Song by Ensiferum
Rip Your Face Off Claire: Trollhammaren by Finntroll
In A Daze Claire: Jillian (I'd Give My Heart) by Within Temptation
Sleepy Claire: Eva by Nightwish
That is just a short list.
Just on an average day, I tend to listen to Blind Guardian, Within Temptation, Ensiferum, Týr, or Flogging Molly. They basically sum up the music which would, I suppose, would reflect me.