Gaming Music...

[Arkhangelsk]

Final Fantasy VII. It's epic cause it has Nobuo Uematsu.

 

[Zeldadudes]

Well, IMO Castle Crashers has one of the best music in a game. I mean I still look up Rage of the Champions

Castle Crashers had a very modern Synth based soundtrack that suited it perfectly.
Personally World of Warcraft has an incredible soundtrack even if it is an MMO.
Regardless of those two i think that Bioshock's motif works suprisingly well with the general scenery.

 

[BrainDead]

I love the combat music from the Half Life 2 games. A close runner up is Grand Theft Auto 4 mostly for the epic theme song, Soviet Connection.

 

[CargoHold]

Err... I've never really played Halo, but the Halo 2 soundtrack is really good.
Please don't hurt me.