The grizzled, gray-bearded guy who played piano behind Aaron Neville and Aretha Franklin during their rendition of the national anthem at Super Bowl XL wasn't recognized by most of the broadcast's millions of viewers. But Mac Rebennack, better known as Dr. John, has been a New Orleans music deity for almost half a century. After doing session work for such legends as Professor Longhair and Joe Tex, plus a brief stint in Sonny and Cher's band, Rebennack unleashed 1968's Gris-Gris, a stunning record reeking of swamp funk, psychedelic murk and primordial R&B. His stage getup was just as nuts, but lately, the self-proclaimed Night Tripper has traded in his voodoo headdresses and gator-skin vests for boxer shorts printed with the official design of New Orleans manhole covers, which he sells on his website to raise money for Hurricane Katrina relief. His latest release, Sippiana Hericane, plumbs the same grim topic with sinew, soul and an exclamatory affirmation of life -- all of which have been hallmarks of Dr. John's music all along.