If there's anything that proves Metallica has become a pop culture institution on par with Led Zeppelin and hula hoops, it's the existence of Finland's Apocalyptica. Coming together in the mid '90s, the cello quartet specialized in the Metallica songbook, including head-banging chestnuts like "Enter Sandman," "Creeping Death" and "Harvester of Sorrow." In 1996, the band released its debut album Plays Metallica by Four Cellos. By its second record, however, Apocalyptica started reworking selections from Faith No More, Sepultura and Pantera. Then something strange happened. What started out as really nothing more than a novelty act (a Trans-Siberian Orchestra for real metal heads) evolved into a bona fide experiment in neo-classical heavy metal (a move which makes sense considering both genres worship symphonic grandeur). In addition to featuring all original compositions, 2003's Reflections saw the group collaborate with Slayer drummer Dave Lambardo. Since then the band has also hosted such guests as HIM's Ville Valo, the Rasmus' Lauri Ylonen and vocalist Till Lindemann of Rammstein. Apocalyptica even employ smoke and fancy light shows when they perform live.