I think I like Dan Seagrave's coveres the best. The covers for Dissection - Storm of the Light's Bane, Nile - In Their Darkened Shrines, and all the Immolation covers are cool too, but I don't know who did them.
Black Sabbath - Warning
Metallica - Am I Evil, Breadfan
Cathedral - Solitude
Rainbow - Still I'm Sad
Place of Skulls - Don't Let Me Be Misunderstood
Fates Warning - Sign of the Southern Cross
Slayer - Dissident Aggressor
Candlemass - Black Sabbath Medley
Shadows Fall - Welcome to the Machine