Sure. This list is based on the idea that you don't listen to any of the below, ok? Going from the bottom of my iTunes collection and up:
Warbringer, if you like bands such as Slayer.
Tool. Definitely give them a listen.
Three Days Grace
System of a Down
Stone Sour
Soil
Slipknot
Shinedown
Sepultura
Serj Tankian, his solo work.
Scars on Broadway
Sea of Treachery
Rise Against, not metal, but very, very, impressive Punk Rock, worth at least a listen
Rage Against the Machine
Pantera
Ozzy Osbourne, his solo work, maybe give a care to Black Sabbath
Nine Inch Nails
Nightrage
Metallica
Megadeth
Machine Head
Iron Maiden
In Flames, particularly A Sense of Purpose, their latest album
Five Finger Death Punch, try The Bleeding, good song
Drowning Pool
Disturbed
Dark Tranquillity
Bullet For Valentine, great band, fantastic new metal
Black Tide
Avenged Sevenfold
Alexisonfire
Big list of bands is over now, I hope you find something to listen to out of that.