Abbey Road - Barbarians at the Gates by Immediate Music, or,
Electirc Romeo by Immediate Music, or,
Anything by X-Ray Dog (he does alot of the songs for action movie trailers, go check him out)
MGS 2 theme
Requiem for a Dream
Anything by Steve Jablonsky (Wrote music for Gears of War 1 & 2 and Transformers 1 & 2)
Music from the Command & Conquer Series (Especially Hell March 1, 2 and 3, and the USA Battle Themes from Generals and Generals: Zero Hour)
Themes from any of the Battlefield Series (i.e. Battlefield 2/1942/2142/Bad Company etc)
Starship Troopers Klendathu Drop theme (also the main theme)
and if you go to the Audio Portal on Newgrounds.com you can often find some very nice 'amateur' songs that can be really good
Thats all i can think of right now, good luck, and keep up the good work 