When you think of thrash metal ? aggressive, quick tempos, broad instrumentals and shredding-style guitar riffs ? Metallica probably comes to mind. Its members ? drummer Lars Ulrich, singer/guitarist James Hetfield, guitarist Kirk Hammett and bassist Robert Trujillo ? make up one of the most famous rock bands in the world, having sold some 59 million albums in the United States since 1981, and more than 100 million worldwide.It's hard to believe that a band could be so successful when it failed to find true commercial success until the release of a fifth album, but the path seemed to work for Metallica. That self-titled project (also known as 'The Black Album') was released in 1991. It debuted at No. 1 on the Billboard 200 and for the first time earned the band widespread critical acclaim. It's most recent studio effort, 2008's 'Death Magnetic,' was also its fifth straight album to bow at the top of the charts.If success for a band goes beyond album sales ? and these days, it most certainly does ? than Metallica's road act is the driving force keeping them relevant in today's ever-changing music scene. The veteran group was the eighth-highest-grossing act in the world in 2010, with earnings of $62 million from just 33 shows. Metallica was also part of a string of shows featuring the 'big four' of thrash metal (alongside Slayer, Megadeath and Anthrax) in 2011, though only one of those shows took place in the United States. The band then celebrated its 30th anniversary by playing four shows at the Fillmore in San Francisco in December and moved into 2012 with the announcement the band would be starting its own music festival called Orion Music + More. It took place on June 23 and 24 in Atlantic City, NJ.