Just music.

An example (bands, not individual tunes):
Rammstein
Fear Factory
Consolidated
KMFDM
Ministry
Lunatic Calm
Bile
Sepultura
Pitchshifter
The Future Sound of London
Electric Hellfire Club
Aphex Twins
Synical

Not so loud as to make it hard to talk; ideally just loud enough to be a bit distracting/obnoxious/annoying. Helps keep the edge on the game...

TZ
TexasZombie
http://www.geocities.com/eviloverlord668/afmain.htm
http://www.geocities.com/Area51/Vault/9327/main.html
http://tzngm.blogspot.com/

That which does not destroy me has made a very grave tactical error...