Just so this thread does get some work done, I do have a mix of some of the oddest covers in my collection:
SikTh - Tupelo (Nick Cave)
Ewigkeit - Ea 2000: Out for the Count (Burzum)
Anal Cunt - Staying Alive (The Bee Gees)
Inkubus Sukkubus - I Just Can't Get You Out Of My Head (Kylie Minogue)
Halo of Flies - Deathcrush [Genocide on the Dancefloor Version] (Mayhem)
Type O Negative - Cinnamon Girl (Neil YOung)
Jack Off Jill - Love Song (The Cure)
Amorphis - Light My Fire (The Doors)
The Anti-Nowhere League - Gypsies, Tramps and Thieves (Cher)
Entombed - The Ballad of Hollis Brown (Bob Dylan)
KMFDM - These Boots Are Made For Walking (Nancy Sinatra)
Overlord - Sound of the Underground (Girls Aloud)
Johnny Cash - Hurt (Nine Inch Nails)
Tulus - Space Oddity (David Bowie)
Skyclad - Prime Evil (Venom)
Therion - Summer Night City (Abba)
The Meads of Asphodel - Utopia (Hawkwind)
Dimmu Borgir - Burn in Hell (Twisted Sister)
It is unusual for my lists, in that it contains shameless self-promotion in the form of the Halo of Flies track. Halo of Flies being, of course, me.