Black Sabbath's Tony Iommi is one of only two guitarists (the other being Led Zeppelin's Jimmy Page) that can take full credit for pioneering the mammoth riffs of heavy metal. Born on February 19, 1948, in Birmingham, England, Iommi picked up the guitar after being inspired by the likes of Hank Marvin & the Shadows as a teenager. By 1967, Iommi had played with several blues-based rock bands, and formed a group (Earth) with three old acquaintances from his school days -- bassist Terry "Geezer" Butler, drummer Bill Ward, and signer John "Ozzy" Osbourne. But Iommi's musical caree...