There are obviously many Metal albums out there that perhaps haven't received all that attention as they should have deserved in the first place. I have quite a few in my mind, but am gonna start this topic by mentioning
CYST's
"Concussion Symphony" that was released in 2002 already: awesome, downright aggressive and very riff-driven Thrash Metal is what that record is all about - performed the way I like it best.
Just managed to find and buy a second-hand copy of it for myself, which I am truly happy about.

Awesome dude, Cyst is from my town. See them every chance I get, they just recently reformed and finally released their second album. Really fun band and real cool guys.
Belzebong's
Sonic Scapes and Weedy Grooves is absolutely the greatest album to listen to while stoned out of your mind. It's filled with "hidden" sounds and stuff that you can only really hear clearly when you're high, and the actual songs are fantastically groovy.