For me it was “Decimate the Weak” by Winds of Plague, followed closely by Children of Bodom’s “Blooddrunk”, Trivium’s “Shogun”, and others I can’t remember right now for some odd reason.
What are yours?
I don’t realy have any favorite albums but one of my favorite songs of 2008 was ‘robots 3 humans 0’ by Norma Jean.
Slipknot-ALL hope is gone:D 
Death Cab for Cutie - “Narrow Stairs” is the only one that comes to mind.
(I liked Angels & Airwaves - “I-Empire” better, but was technically 2007)
Edit: Forgot about MGMT - Oracular Spectacular
My favorite Albums of last year in no paticular order,
MGMT-Oracular Spetacular
TV on the Radio-Dear Science
The Cool Kids-The Bake Sale EP
Vampire Weekend-Vampire Weekend
Apparently I’m the only one who doesn’t listen to metalcore or Indie.
The Way of All Flesh - Gojira
Gods of the Earth - The Sword
01011001 - Ayreon
Lazarus Bird - Burst (alright, they’re metalcore, but they’re not the generic crap metalcore)
Has to be Atmosphere “when life gives you lemons, you paint that ‘stuff’ gold”. Its such a well thought out album that really shows Slug’s story telling ability. The Sad Clown EPs that came out in roughly the same time are easier to get into and may be more ‘enjoyable’, but Lemons is just on a different level.
i liked most of nickelback’s black horse, and all that i heard of metalica and ACDC. i think thats it…
A Hundred Million Sun’s- Snow Patrol
Rise and Fall, Rage and Grace- The Offspring
Viva la Vida- Cold Play
Rise and Fall, Rage and Grace- The Offspring
Reach- Eyes Set to Kill
Oracular Spectacular- MGMT
Michael Jackson - Thriller - 25th Anniversary Edition
The Ting Tings - We Started Nothing
The soundtrack to Twilight
Those are just a few favorites that were actually released in 2008.
I discovered a lot more, but they have been out for a while such as Muse’s Black Holes & Revelations. Good stuff!
Mindless Self Indulgence - If
Amon Amarth - Twilight of the Thunder God
Opeth - Watershed
Both of those were good albums, but I didn’t like them compared to either bands’ earlier works.
On the other hand, it would be hard to any album to live up to Blackwater Park, which is still my favorite album of this millenium.
Huh, can’t believe I forgot about Twlight of the Thunder God. That was one of my favorites as well. And A Sense of Purpose by In Flames and Overcome by All that Remains.
Narrow Stairs- DCFC
Day and Age- The Killers (can’t believ no one has said that)
I’ll probably think of more, but those are my two faves.
How did nobody say Death Magnetic - Metallica?
Agree with this statement totally (moreso with Watershed than with Twilight of the Thunder God, which I think is right up there with their best).
Pitchfork media summed up my thoughts on the album pretty well when they said, “But [Rick Rubin’s] intent was well-meaning: get rich, fortysomething rockers to recall themselves as hungry, twentysomething metallers. In the real world, this is called a midlife crisis.”
They tried, but it just wasn’t the same. “My Apocalypse” and “All Nightmare Long” came close, but the rest was just a mess of riffs, solos, and awful drumming.
James can still write some terrific riffs, but they can’t write songs the same way the used to. Now it just sounds forced, it utterly lacks any flow. Maybe it’s the lack of Burton, or the lack of Mustaine. Either way, it’s hard to listen to. 
Sorry, you just triggered my rant. It took a lot for me to abstain from commenting on the In Flames and Bodom albums (both of which were massive letdowns, although In Flames was to be expected considering how they’ve been playing since 2000). Death Magnetic just broke my camel’s back! 
There really aren’t any new releases that I pay attention to (mostly because I listed to 60’s-70’s rock) but AC/DC’s Black Ice was decent. Also Rush’s Snakes & Arrows Live was good.
While I agree Blooddrunk isn’t Bodom’s best album, it’s still up there for me. And A Sense of Purpose is one of my favorite In Flames albums. All a matter of preference I suppose.