other than the obvious songs i'll say justin timberlake "sexyback" nothing really sounded like it before it came out and definitely still sounds fresh today
As Dephira put it... going by a broad definition of pop:
Madonna - Like a Prayer
Michael Jackson - Beat It
Janet Jackson - Together Again
Blondie - Call Me
Eurythmics - Sweet Dreams (Are Made of This)
The Beatles - Here Comes the Sun
Queen - We Will Rock You
Elton John - Bennie and the Jets
Gloria Gaynor - I Will Survive
Mariah Carey - We Belong Together
Cyndi Lauper - Girls Just Wanna Have Fun
Whitney Houston - I Will Always Love you
Los Del Rio - Macarena (Bayside Boys Mix)
Mariah Carey & Boyz II Men - One Sweet Day
Coolio - Gangsta's Paradise
Hanson - MMMBop
Spice Girls - Wannabe
Celine Dion - My Heart Will Go On
Cher - Believe
Brandy & Monica - The Boy Is Mine