Actually I personally find a bit of heavy metal serves better for blasting
My suggestion? "Laser Cannon Deth Sentence", by Dethklok. It's actually pretty perfect. When the Cardassians turn tail and try to flee as the "DUH-DUH-DUH-DUH-DUH-DUH-DUH-DUH-DUH-DUH-DUH-DIE!!!" begins, the effect is truly sublime.
In between combats, though, I've been favoring techno (anything Underworld, with Fatboy Slim's "Sunset (Bird of Prey)" for hunting Klingons) for in-system travel, and Stone Temple Pilots' "Interstate Love Song" for the long slog out to the nebulas.
I use Winamp, but guess the process is the same for iTunes:
1, At your liesure, make a playlist in Winamp.
1(a), Start Winamp
2, Start playing your playlist (set repeat / random as you wish)
3, Start STO lancher and Engage!
4, Once you get past Log in and are playing, go to the audio options and select Winamp as your music (media?) player and save / exit options
5, Start the ingame music player and enjoy your playlist while gaming - music player allows playlist manipulation
As I do not have iTunes, I can only speculatet that you can adapt the process for said.