Feist

When Leslie Feist played Bonnaroo in 2007, it was a few months before that ubiquitous iPod commercial vaulted her to stardom. After that, you might've thought she peddled twee adult-contempo rock, but last year's Metals was a patently bleaker affair that showed she can do the dirge thing too. And, of course, there's the matter of her beautiful voice, which can effortlessly turn a melancholic verse into a lilting chorus.