This song also should have been mentioned at some point.

http://www.youtube.com/watch?v=EdA_j-MlYqI

Don't judge me but I use this a Video Game Song. It's awesome http://www.youtube.com/watch?v=5AyJyoiH5-k

I have it down between two songs:

1) Night of Nights, Touhou
I've never played the game myself, but this song...THIS SONG...it's so ridiculously awesome.
2) Black Dragon Medley, Fire Emblem
I discovered this just yesterday, when I was playing SSBB. Because, you know, you have to grab all the discs. All of them. I put it on, and all of a sudden, all battles became 20% more epic.

http://www.youtube.com/watch?v=FSZBcPRQpO8

http://www.youtube.com/watch?v=nRbROTdOgj0

Edit: I have to say the music from The Legend of Zelda: Skyward Sword is epic, although it does get redundant at some points.