Cassie (left) and Beyoncé    (Photo: Frank Micelotta/Getty Images; David Bailey)

8. Hot & Cold R&B
Fire and ice: That’s what R&B’s biggest star and most surprising newcomer brought to the table this year. Beset by nasty rumors about her relationship and her music, Beyoncé rushed into the studio and turned out B’Day, a furious document of a superstar asserting her independence. Twenty-year-old Cassie, on the other hand, made a lack of personality work in her favor, riding the spacey minimalism of producer Ryan Leslie’s beats—and a little help from MySpace—all the way to number one with “Me & U.”