By my faves?
Beyonce: Check On It, Deja Vu (?), Irreplaceable, Beautiful Liar, If I Were a Boy, Single Ladies
Kanye West: Gold Digger, Stronger, Love Lockdown, Heartless, E.T.
Rihanna: Pon De Replay, SOS, Umbrella, Take a Bow, Disturbia, Live Your Life, Russian Roulette, Rude Boy, Love the Way You Lie, Only Girl, What's My Name, S&M, We Found Love
Eminem: When I'm Gone, Crack a Bottle, Not Afraid, Love the Way You Lie
Jay-Z: Deja Vu (?), Umbrella, Run This Town, Empire State of Mind
Mariah Carey: All I Want for Christmas Is You, Don't Forget About Us, Touch My Body
Shakira: Hips Don't Lie
Jennifer Lopez: On the Floor
Nelly Furtado: Promiscuous, Say It Right
Yes - the #1 song of the decade "We Belong Together" peaked at #2 on iTunes.
And just to make Selena fit in here....
#1 on iTunes Latin Albums: Enamorada de Ti