I COULD do an all-time list, but I'm way too lazy to doublecheck which songs went to #1, so I'll just stick with this decade, since that's what I'm mostly well-read on.

Plain White T's - Hey There Delilah
Beyonce - Irreplacable
Rihanna - S.O.S.
Sean Paul - Temperature
Nelly Furtado - Promiscuous
Mariah Carey - Don't Forget About Us
Usher f/ Lil' Jon and Ludacris - Yeah
Beyonce f/ Sean Paul - Baby Boy
Nelly f/ Kelly Rowland - Dilemma
Christina Aguilera, Lil' Kim, Mya & P!nk - Lady Marmalade

Los Lobos - La Bamba
Milli Vanilli - Blame it on The Rain
Milli Vanilli - Don't Forget my Number
Snow - Informer
Los del Rio - Macarena
Ricky Martin - Livin la Vida Loca
D4L - Laffy Taffy
Terror Squad - Lean Back
Cuture Club - Karma Chameleon
Tony Basil - Mickey

no really

Men at Work - Down Under
Montell Jordan - This is How we do it
Janet Jackson - Together Again
Ace of Base - The Sign
Bryan Adams - Heaven
Next - Too Close
Enrique Iglesias - Be With You
Shakira ft Wyclef Jean - Hips Don't Lie
Marvin Gaye - I Heard it Through The Grapevine
Gwen Stefani - Hollaback Girl
Nelly Furtado - Say it Right