Well now, I'm glad you asked. I have a few theme songs for Maddy, depending on my mood and her's.

Modest Mouse - Dashboard and King Rat
The Hives - Antidote
Ke$ha - Backstabber (I have no shame admitting I like Kesha.)
deadmau5 and Gerard Way - Professional Griefers
Silversun Pickups - their entire discography, really, but Future Foe Scenarios in particular
George & Jonathan - Witch's Brew
Monomer - Better Living Through Dysgenics
bLiNd - Slam Shufflin'

Just ones I could think of off the top of my head, really.