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.