Disappointed that I haven't seen two of the best mentioned:
Gonzaga - Mother (Danzig)
G-sot - Iron Man (Sabbath) although he came out to Acca Dacca in Oz which was a good substitute! 
Sub
Pantera walk it's always fitting shit it's tailored made for it. I'd say any Tera except the shit from the early 80's high metal is and will forever be a terrible trend.
*hair
Jeff Monson's Imagine entrance was epic.
Has anyone used "Psycho Killer" by the talking heads? Seems like an easy choice. Also anything by Stiff Little Fingers would be cool.
I am sick of "Run This Town".
Between the GSP/Kos commercials and Aldo; it has to go.
I'd rather hear "Rock This Town" as Brian Setzer walks out alongside a dancing Amir Sadollah.
I'm really sick of the most aggressive rap or metal music and then the fighter fights "safe".
Gonna use "kill" music?
Don't fight to go 5 rounds and clock watch.
If you want blood, you got it by ac/dc
How can you have this discussion and not start with Wand and Sandstorm? Seriously.
Big Nog's use of Gimme Shelter has been awesome. It was funny when Joe is heaping his normal praise for Pride legends during his entrance against HH when it apparently hit him how awesome the song works for an entrance.
Bisping's entrance to London Calling was fucking fantastic. The fact that it followed Hammil coming out to Born in the USA added something, too, but The Clash don't really need any help. He should never have changed.
Has anyone ever use The Immigrant Song? I think that would work well.
Mir - Amazing
Penn - Hawaii epic doom song
Wanderlei Silva - Sandstorm
Dan Hardy - England belongs to me
Shogun - Sail
Bonnar - Eminence Front
I think it was Tamdan McCrory who came out to Dimmu Borgir - Puritania.
Now that's a great walkout song, I feel, but not when you have the physical appearance of a champion Starcraft player. Perhaps for somebody like Brock Lesnar :D
Someone (Hellboy?) used this and it was amazing
BrettAwesome -boblazar - Somebody walked out in ufc to "stupid kid" by alkaline trio a few years ago, that was sweet
Guida.
Can't believe i'm the first to mention Eminence Front, used by Bonnar and formerly Marquardt. The most badass walkout music ever. Also pop for Hendo using Lunatic Fringe, probably the only guy that can pull it off.
Randy came out to Lunatic Fringe and seemed to fit him wel.
I really liked Hendo's "Made in America" walkout vs Shogun
JeffersonDArcyChoke - I am sick of "Run This Town". <br><br>Between the GSP/Kos commercials and Aldo; it has to go. <br><br>I'd rather hear "Rock This Town" as Brian Setzer walks out alongside a dancing Amir Sadollah. <br><br>I'm really sick of the most aggressive rap or metal music and then the fighter fights "safe". <br><br>Gonna use "kill" music?<br><br>Don't fight to go 5 rounds and clock watch. <img src="/images/phone/apple.png" alt="Phone Post" border="0" style="vertical-align:middle;"/>
I like quirky entrance music as well. Allthough I would go with Jump, Jive, Wail as a Brian Setzer song.
My favorite walkout right now is I think Brillz that walks out to Bro Hymn. I'd also like to see someone come out to some Sublime or Nirvana. Either Santeria or Sappy I would suppose.
I personally walk out to "if you're gonna be dumb you gotta be tough" by Roger Allen wade
The most fitting was when Rampage came out to "Break the Law" by Three 6 Mafia for his fight with Matt "The Law" Lindland. Both Jackson and 3-6 are from Memphis too.
I walked out to A Warriors Call by Volbeat. I Believe in a Thing Called Love by The Darkness was a close second lol. 
I'm sparring partner for a guy who wants to come out to "Pretty good at drinking beer" for his next fight.
Soundgarden 4th of July it hits heavy has good intro time for fighter to let energy build and it fucking rocks.