I've been really getting into a lot of Sludge lately, with its intriguing mix of Doom and Hardcore and a generous dollop of 70s Southern Rock.
'Down' ranks high on my list here. Phil Anselmo sounds MUCH better in this band than he did in Pantera, the inherent moodiness of his voice really comes out.
THe following song is particularly good, as its running guitar theme is pure metaled up Lynyrd Skynyrd, of whom I have fond memories from my youth. It's a song I love to play when feeling depressed and bitter. It has a wonderful Southern swagger to it.