John Legend is modern R&B's classiest male singer, bringing old-fashioned suavity to hip-hop soul; the Roots are the world's most versatile (and maybe best) band. Together, they have made a brilliantly conceived and executed album, reviving music from the Nixon-era heyday of politically engaged R&B. Bustling through funk, Philly soul and gospel, taking on songs famous (Marvin Gaye's "Wholy Holy") and obscure (Mike James Kirkland's "Hang on in There"), Legend and the Roots capture the old feeling of protest and uplift while updating the sound. They're not imitators — they're heirs.

“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."