mmmm. just had a thought on this.
possibly a series of models that would morph? or you could even use LOD's to condense them into a sort of animation.
like you could have a big sphere, collapse to point, explode in a star then fade or something, like from Starfox 64 (fun as hell in P64 with FS2 controls).
or even have a big to small explosion with a huge ring that would shoot out and collide with other ships, doing massive damage.
you could probably modify the fireball.tbl file or something new with the animation series, or even .pof series if you can't (or don't feel like) implementing animations in them.
I'm still pretty ignorant to the .pof specifications and abilities, though, so...
(btw, this has probably been asked
before, but are animated backgrounds possible? I've tried but the .ani's don't show up in FRED2, I was thinking of forcing the name change in the .fs2 file itself.)
probably gonna go make a post now on atmospheres, slight fred modifications and something else, subject may vary or not occur at all

Bob