Just listen to any Empyrium CD.. I really tried to get in to it. It's just so fucking slow and quiet... You barely even notice it's on. Some good melodies hidden around in there though.
The slowest song is performed by the one and only Die Hard Ultra slow neckbreaking Doomgods on this fucking planet: CROWBAR and it's called "Dream Weaver"
if you have heard this song, My dying bride sounds like standardblackmetal.