Here are the groups I listen, mainly while playing DotA... (in alphabetical order) They are all ownage groups, if you love Metal...
Arch Enemy
Avenged Sevenfold
Axenstar
Bad Religion
Breaking Benjamin
Children of Bodom
Dark Tranquility
Dimmu Borgir
Disturbed
DragonForce
Dreamtale
Drowning Pool
E Nomine
Elvenking
Ensiferum
Fintroll
Godsmack
Hammerfall
Imperanon
In Flames
Kamelot
Korpiklaani
Linkin Park
Lordi
Mors Principuim Est
Nightwish
Papa Roach
Rammstein
Rhapsody
Rob Zombie
Samael
Skyfire
Soilwork
Sonata Arctica
Stratovarius
System of a Down
Three Days Grace
Trivium
Wintersun