the_wolfs_howl, you do not know the meaning of epic until you see this album cover:
Amon Amarth-Twilight of the Thunder God
This album cover simply screams at you from its place on the shelf, pleading you to buy it simply because it looks cool. And it is.
Then there's this one:
Blind Guardian-Nightfall in Middle Earth
I love the way this depicts Morgoth sitting on his throne in Angband, with the Silmarils in his crown.
And:
Showbread-The Fear of God
It's a Showbread album. 'nuff said.
And the best one of all is:
Pink Floyd-The Dark Side of the Moon
Does it need a reason? This is the best because it captures the eye with a spot of color shooting out of a prism on an entireley dark background. It is the simplest, but definitley the best of all that I've listed here.
edit: Metallica's ... And Justice for All has a great album cover too, but I'm not sure if I can post it or not. I like the symbolism and how it relates to the album's lyrical content.
Here's another one:
And did I buy this CD just because the cover looked that awesome? Yes I did.