I listen to a lot of music. And something I do kind of unconsiously is connecting music to other things i like. So, because MGS occupies basically 80% of my brain, there's a lot of songs that remind me of different characters. Here's some of them, with links to Youtube uploads so you can listen yourself!
(I would eventually like to make the songs listenable on the site without having to link them.)

RAIDEN

Mchngrl vs. Wlfgrl-Machine Girl
DAMAGE SUPRESSOR-Black Dresses
TELL ME HOW U FEEL-Black Dresses
World Comes Tumblin' Down-The Distillers
Doll Parts-Hole
Hit Eject-The Garden
Vampires Will Never Hurt You-My Chemical Romance
I Never Told You What I Do For A Living-My Chemical Romance
Wolf-Angelspit

SOLID SNAKE

Realign-Red Vox
Inbetween Days-The Cure
The Last Song-Sleater-Kinney
Unconditional Love-Against Me!
Black Me Out-Against Me!

REVOLVER OCELOT

Stray Bullet-KMFDM
Sailor in a Life Boat-EURINGER
Accuracy-The Cure
Wrong Number-The Cure
Hang 'Em High-My Chemical Romance
My Cat-Jack Off Jill