While many of their ’90s contemporaries have become but nü-metal memories — Fred Durst, où es tu? — Korn are still proving their n?-mettle. To tide us over until their eighth studio album, Korn offer their MTV Unplugged. Singles ”Freak on a Leash” and ”Blind” are softened in their acoustic incarnations, though frontman Jonathan Davis still sounds like the Cookie Monster on a Toll House binge. And a cover of Radiohead’s ”Creep” and a duet with Cure frontman Robert Smith come off, alas, like unpopped kernels.