System of A Down is a very unique alternative metal band from Armenia. They mix strong political beliefs into their often unintelligible lyrics. All of the members have a unique style of playing their instruments, and Serj Tankien has one of the most unusual voices in popular music today. Who cares if they're pop. If they make good music, it shouldn't matter. The Beatles were pop, but they are one of the most influential bands ever. Oh, and by the way... the person who said that they use Drop-D
is only half right. They play in Drop-D tuning one whole step down.
None that I can think of.