I haven't posted any metal for a while, so here is some uber-heaviness. Ufomammut are an Italian 3 piece, augmented live and on record by tapes of theremin, synth drones and movie samples. They specialise in a kind of pounding psychedelic stoner sludge, which is most effective live. I would say they were the second best live act I saw last year - a close second behind The Master Musicians Of Bukkake. They achieve their superb effect with repetition, tightness and dynamics, as well as the aforementioned atmospherics; but they also have a mean guitar sound - ultra heavy and bludgeoning. Their grasp of dynamics is becoming more consummate with every album, as far as I can tell: the last album 'Eve' is basically a suite of tracks that don't deviate a great deal from the main blueprint, but it works fantastically as a whole, and is thoroughly recommended. This one is their debut from 2000, and is out of print - it's a good place to start, and a brilliant slab of mammoth spaced-out sludge groove.
EDIT: Ufomammut are playing in London on Thursday October 6th - the Purple Turtle in Camden. I highly recommend this gig if you like all things heavy and psychedelic!