Man, I don't know, they don't make metal like they used to, but there are some decent mainstream albums in this decade, just to name a few:
Down - Down II: A Bustle in your Hedgerow
Children of Bodom - Follow the Reaper, Hate Crew Deathroll
Exodus - Tempo of the Damned, Shovel Headed Kill Machine
Kreator - Enemy of God
Anthrax - We've Come For You All
Megadeth - The System Has Failed
Lamb of God - As The Palaces Burn
I'm pretty apathetic about new music. Underground death metal is good, but you rarely hear anything revolutionary; it's just good music to break up the monotony of strictly listening to classic thrash/death metal. I'm pretty slow when it comes to hearing about new metal albums out there.
As far as general rock goes, they don't make 'em like they used to there too. By that, I mean good stuff: Rage Against the Machine, Alice in Chains, Smashing Pumpkins, Soundgarden, etc. I stopped listening to mainstream rock radio some 8 or 9 years ago because even rock music was being watered down greatly to either emo or the kind of indie sounding rock.