Dave Lombardo loves to jam! I mean, have you checked out Fantomas? They sorta rule hard.
So, when an LA metal mariachi band named Metalachi (natch) asked him to come up and jam on Slayer's undisputed biggest hit, "Raining Blood," Lombardo was all game.
[youtube]http://www.youtube.com/watch?v=hzp_7U7R0OM[/youtube]
How awesome is this? Metalachi describe themselves as "a five-piece ensemble of classically trained mariachi musician brothers, but taking their cues from Kiss, GWAR and Rob Zombie."
A quick Youtube search uncovers some amazing covers of "Sweet Child O Mine," a Metallica medly, and Faith No More's "Epic".