[Dextrimental]

Hmmm... Good thread..

Groove Metal: Vulgar Display Of Power - PanterA
Thrash Metal: The New Order - Testament/Kill 'Em All - Metallica
Heavy Metal: Black Sabbath - Black Sabbath
Power Metal: (Modern) The Book Of Heavy Metal - Dream Evil
(Classic) Somewhere Far Beyond - Blind Guardian/Holy Diver - Dio
Progressive Rock: A Night At The Opera - Queen/Machine Head - Deep Purple
Progressive Metal: Still Life - Opeth/Images And Words - Dream Theater
Death Metal: Scream Bloody Gore - Death/Altars Of Madness - Morbid Angel
Technical Death Metal - The Sound Of Perseverance - Death

Those are just off the top of my head, way too hard to say definitively as these are all open to interpretation.