Lots! Yes Kelly Clarkson & Coldplay. Plus LOTS of other stuff. Are we talking strictly pop? What about Dylan or Bowie or The Beatles or The Boss? It's pretty mainstream stuff but not really closet-listening material...hmmm. Or music that's mainstream but still considered respectable like The Arcade Fire or Arctic Monkeys? OK, I'll stick with stuff that is pure poppy goodness:
Madonna. Grew up with it. Still love it. Shut up!

Hit Me Baby One More Time by Ms. Spears. Her only good song methinks.
Prince
Dixie Chicks (You know you love it!
Dwight Yoakam

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Lots of stuff is questionable--