When I'm not on comms for deadly important reasons (see: combat, purposes for hearing the FC) I usually have some music playing. I live for music: I'm a professionally trained mezzo-soprano, perfect pitch, etc, etc. I get depressed if I've got nothing playing during the quiet times, and what I listen to can affect my mood. On my iTunes, I've set up different playlists with mood themes and specific ones for each story I'm working on.
Eve has its own soundtracks: one for travelling, one for combat. I mostly only use these when I'm on my alts, since they give me the freedom to roleplay a little, to view Eve as if I were an actor in a sci-fi drama.
Well, that is essentially what each of us is ^_^
Eve, for me, has a tribal feel: lots of djembes and doumbeks, irregular rhythms and complex patterns, overlaid with grungy guitars, airy synthesizers and introspective or rebellious vocals as appropriate. Sometimes it goes drum'n'bass or even jungle, sometimes it's more ambient with a bit of a sad touch.
My Eve playlists include tracks like Arianrhod and Sredni Vashtar by Faith and the Muse, Papua New Guinea by Future Sound of London, Above&Beyond's Indonesia, multiple songs from Loreena McKennitt, Hybrid, Fields of the Nephilim, Opeth and The Prodigy, Junkie XL and Dead Can Dance. I use other soundtracks to add an orchestral touch, mostly The Crow, The Fifth Element, Firefly (betcha didn't see that one coming ~_^) and most recently, Iron Man.
What's your Eve Soundtrack?