I have a lot in mind:
Chantal Kreviazuk
Alanis Morissette
The Corrs
Tiffany Arbuckle (Plumb)
Marie Digby
Taylor Swift (I know most of her songs are love songs but you have to give her credit for her fantastic songwriting capability.)
Sarah McLachlan
Sara Bareilles
Regina Spektor
John Lennon
Chris Carrabba