The Angelic Process-Weighing Souls With Sand Really good shoegazer meets metal stuff that will keep the neighbors up. Sounds like Jesu meets the Swans.
Agalloch-The Mantle Black Metal with folk influences and great gothicesque passages. Sounds like Katatonia meets Death In June in their prime, and great for cold winter nights.
Alice In Chains-Facelift, Jar of Flies, Sap, and the Self Titled "But gary, that's grunge!" Shut up, it's metal to me.
Slayer-Seasons in the Abyss No metal list would be complete without Slayer. You really can't not love an album with "War Ensemble" though.
Enslaved-Isa Call it what you want (Black Metal, Viking Metal, whatever), it's really good, with progressive rock overtones to match.
Nile-In Their Darkened Shrines Really good technical Death Metal, with Lovecraftian undertones (you knew I'd love that), trible drumming, choirs, and more.
Symphony X-Divine Wings of Tragedy I normally don't care for Symphonic metal, but this is actually a good album. I love the keyboard work on it.
Gorgoroth-Ad Majorem Sathanas Gloriam I normally don't like these guys, but this is a pretty impressive album, with awesome drumming, and a frontman (Gaal) who actually sounds scary. Also, it's quick and to the point, with no filler at all.
White Zombie-Astro Creep 2000 I always liked this more than La Sexercisto, as it gets the whole sleazy comic book vibe down better.
Melechesh-Emissaries Black Metal filled with middle eastern rhythms (they are from Jerusalem), killer riffs, and even a song with tabalas.
Amorphis-Elegy The last Death Metal esque album they did, with awesome riffs, acoustic guitars, prog rock keyboards, and more.