No man alive – well, no 15-year-old Canadian -makes ladies squeal like Justin Bieber. He's 65 inches of pure love panther, with sensitive-man bangs and a voice like Joey Mclntyre getting savagely beaten by the Auto-Tune police. On the jazzy "P.Y.T." rip "Bigger," the Bieb confesses, "I was a playa when I was little" – playa of what, Pokémon Battle Revolution? But who could deny "First Dance," where Usher drops Justin at the prom so he and his Bieblette can get to "rockin' back and forth under the disco ball"?

Key Tracks: "First Dance," "Bigger," "Love Me"

“I'm Yours”

Jason Mraz re-emerged after his disappointing second album with this lead single, a Jack Johnson-esque ditty about giving yourself fully to someone else. The success of the reggae-tinged song (it earned two Grammy nods and a spot on the Billboard singles chart for well over a year) was something the folk-pop singer never predicted when he wrote it in 15 minutes at home. "I played a happy-hippie chord progression that would probably work without 50 different Bob Marley songs," he told Rolling Stone. "I thought, 'It's too novelty. This is a nursery rhyme,'" concluding that "you can never guess what's gonna be a hit."