Also saw that Dresden Dolls cover of "War Pigs" live, and it did kick a lot of ass indeed.
Also liked Les Claypool's cover of "Shine on you Crazy Diamond." "> and Faith No More's "I started a Joke." "> I have a special vinyl single of Faith's cover of "War Pigs" - pretty awesome.
[Edited to add: I'll figure out what embedding fail I have failed later. Tired, brain hurt. Fail.]
When it comes to slightly offkilter covers, my mind immediately goes to Me First and the Gimme Gimmes. But someone already posted them, so here's Pomplamoose: