ENT. The opening song for Enterprise should have been "Rock You Like a Hurricane" by the German band the Scorpions.
Here is a great suggestion for an alternate ENT theme song - but one that would only work for the Mirror Universe episodes: http://www.youtube.com/watch?v=PccZebZKF9E
As to the regular ones - maybe the theme song have been tolerable if they had just found a better singer? Hmmm, who could it be? Who is a Trek fan in the world of music?
Iggy Pop was on DS9, maybe they could have asked him to sing it
though I can't imagine him singing "Faith of the Heart"... maybe something like:
So I take a little bad with the good
It ain't just black and white
You've got to deal with the real
Oh, living on the edge of the... quadrant
*Maybe this could have been the DS9 theme song...