all kinds of metal/rock realy. not anything specific beyond that 
Whatever is in my WinAmp playlist or my Last.fm 'personal' or 'mix' radio. I've been letting last.fm track my listening habits for several years now so my radio gives me a pretty good mix of favorites- past, present and all-time.
Top 100 according to Last in the spoiler ...
Tool - (#1 by far... just sayin')
A Perfect Circle
Puscifer
Type O Negative
XTC
Woven Hand
Against Me!
Queens of the Stone Age
16 Horsepower
Isis
Def Leppard
AFI
Slim Cessna's Auto Club
Godsmack
Nine Inch Nails
Johnny Cash
Stone Sour
Queensrÿche
Xzibit
Better Than Ezra
Shinedown
Pantera
10 Years
Weezer
Tori Amos
The Cardigans
Dead Poetic
Hellyeah
Depeche Mode
Pop Will Eat Itself
Lacuna Coil
311
Everlast
Eagles of Death Metal
Adele
Fear Factory
The Listening
Frente!
KMFDM
Journey
inaeona
Helmet
Queen
Henry Rollins
Collective Soul
Incubus
Bill Hicks
Gnarls Barkley
Eminem
Just Add Water
Daft Punk
Primus
Billy Joel
Marilyn Manson
Ramones
Paramore
Matisyahu
The Cure
Korn
Linkin Park
Beatallica
Sunna
Guns N' Roses
Orgy
Tricky
Nirvana
Pink Floyd
Damageplan
Slipknot
Social Distortion
Corrosion Of Conformity
Ministry
Jurassic 5
Course of Nature
Cake
Dead Kennedys
Tantric
Radiohead
Trapt
Richard Cheese
Cracker
Led Zeppelin
Flogging Molly
HIM
Lostprophets
House of Pain
Machines of Loving Grace
Cog
[unknown]
U2
System of a Down
Phil Collins
Seven Mary Three
Rasputina
Sublime
Milla
DMX
Garbage
White Zombie
The Police
KMFDM. What better music to listen to while doing industrial stuff than industrial?
EDIT: Saw saul_goodes list, damn what a collection man! Doubleplus good! OCremix has some good music to accompany games, favoring armored core tribute album atm.
Gah, who needs external music when you got C418
Usually I don't listen to music but have something playing (youtube vid I downloaded, actual tv show, etc..) on the home theater machine to my left.
however when there's nothing like that I turn to rockradio1 (streaming internet station)
listening to C418, the old skool radio, or some wubstep 
Mostly rock, metal and punk:
B182, Sum41, Foo Fightersm, Rise Against, Skillet, BFMV, etc)
Orchestral music too:
Mostly use it for filmmaking (Think X-ray Dog, Two Steps from Hell, Audiomachine, West-One and immediate music)
Some undefined other music. No direct dislike/like of anything actually.
Hmm,
Especially whilst flying/battling hordes of enemies, it seems to match the atmosphere of the game.
Nothing beats pure PvP action with this kind off in the background: (Ol'brick days)
http://www.youtube.com/watch?v=VdXRK4KcSSs
Pretty much metal and rock, occasionally something that is playing in
the radio. Also some music that is pretty much undefined and even C418
in minecraft if i happed to get a record somewhere. Quite a lot of stuff
from Saul_Goodes list actually.
Off topic:
Something similar which is 10 years older and better: Surprise. Propably the only game that I have yet played more than minecraft. Bought it for 8€ 9 years ago and it killed my processor.And the game still works 
.
