Thought I'd post this and see what other good covers out there I didnt know about as well as find out some of yalls faves. So heres mine.
Iced Earth's cover of Hallowed Be Thy Name originally done by Iron Maiden.
[YOUTUBE="2PVbzO0X6dU"]Iced Earth's: Hallowed Be Thy Name[/YOUTUBE]
Edit: AHA! For your benefit I decided to remember how to embed videos!