"Let's Chill"

This sparkly slow jam literally starts in the club: It's late and Amerie is ready to call it a night. But then she spots club-weary crooner Trey Songz, who offers the leggy songbird his immodest lullaby: "Rockabye baby when the beat drop/ don't let your friends know we about to creep off." When that beat drops and desire goes boom, Amerie and Trey soar, showing that like Donnie Hathaway and Roberta Flack before them, the pair have some serious harmony.