Jennifer Lopez's journey from New York's 6 Line train to megastardom was guided in part by her ability to transform the Latin freestyle of her youth into massive tracks featuring hip-hop heavyweights. Her silvery voice, Bronx-born sass, and chemistry with big-name collaborators like Ja Rule helped tracks such as the buoyant “I'm Real” become radio staples, while her teaming up with Pitbull created an unstoppable Latin pop powerhouse. But she can hold her own solo, too, as evidenced by dance-floor anthems like “Do It Well” and “Waiting for Tonight.”