The Red Chord (out of Boston) is straight up hardcore Death Metal.
Job for a Cowboy (out of Arizona) is also Death Metal, but with two guitars and some serious talent they sound musically more like old school Metallica.
Gwar. . . not sure if I can describe them at all. Imagine being at a SciFi convention, a metal band in Klingon armor comes on stage- and then you drop acid.
These guys are seriously bizarre- they make "South Park" seem like wholesome family entertainment, but always with tongues firmly in cheek. A psychologist could write a doctoral thesis on all the imagery and archetypes in their seriously sick and twisted performances. But- they rock!