Intros to song a that make you feel like a bad ass.
I have "whole lotta love" led Zeppelin as a ring tone. When it goes off I just feel pumped.
Like the song you could have in the movie when the hero is about to go all one man army and shit.
I'm talking...
Thunderstruck ACDC
High ways to hell ACDC
"Short changed hero" The heavy
"Hysteria" Muse
"Sad but True" Metallica
What else? Songs that grab just you. 
Last by NIN...then I get really pumped about 45 seconds in when the guitar line kicks in.
System of A Down - "Toxicity"
Roster by Alice in Chains 
Overkill - Motorhead
I wanna be your Dog - The Stooges
^"And now at 6 6 from North Carolina, Michael Jordan"!
and then the rest of the roster?
For me, its the wah ah ah ah song. Down with the sickness maybe? I often yell it in the shower.
Rebellion by Gravedigger :)
It is so horribly corny that it is glorious. I think Hansen used it as an entrance song in Bushido.
Voltron theme
Hatredcopter - Dethklok
Destruction Overdrive - Black Label Society
Hell Awaits - Slayer
Korn
Blind
All Shall Perish - The Last Relapse
It's the fucking goat intro for a metal core(ish) song. The entire song is badass too.
http://youtu.be/ZLf22DItDIY
T.B Sheets by Van Morrison !
Walk-Pantera
Barnicale Bill - Roster by Alice in Chains
.
Rammstein- Sonne would make the perfect entrance!
Season Of The Abyss - Slayer
How has "Welcome to the Jungle" not been said yet?
Intro to "we gotta know" Cro mags