Also, Baba Yetu from Civ 4.

Nice choice.

Opening theme from original Deus Ex.

+1

Yeah, I'll give Bethesda's theme tunes this: they always reflect very well on the game you're playing.

i love Morrowind main theme

Marioweeday is nice

yep, Uematsu Nobuo is the man, the music of FF is just amazing.

+1

Specifically, Hell March 2. And Drok.

That part where he screams "What is your profession?!" ?

Yea,i screamed too.

The Battle for Middle-earth games share music and, while I think it's strictly random, the music nine out of ten times seemed to reflect and complement the epic defence I waged or four hundred Rohirrim galloping to battle. The Two Towers and Return of the King also got basic but very fun hack-and-slashers.

Oh man, when that started playing in ME3, I got shivers.

+1 and this

Oh yeah!

Ornstein and Smough boss battle theme from Dark Souls

awesome theme :)

+1 to this! Epic , Oh shit, run, the best PoP game and themes.

I also love Deus EX:HR and Dungeon Siege themes.

+1