There's probably a fugue discussion somewhere on http://www.therhombus.com
I don't know if anything by the Dead exactly qualifies as a fugue... Slipknot? I'm kinda thinking King Solomon's or the bridge of Cryptical might just barely be a fugato
(a work or section of a work resembling a fugue but not necessarily adhering to the rules of one)... but the rules seem a bit vague. A cover, but is Freedom Jazz Dance a fugue of sorts?