Excellent ideas in the variation of effects and sounds. You're right, we can't go too crazy ADDING new animations... (though we might consider it for those ubersystem people [not me, but someday]) but how about changing the existing stuff?
I've been looking at the particle system code, and it looks like there's some great ways to customize things that could be opened up. One of my ideas involves using an 'effects table', much like the weapons table. As ships can pick "some" weapons, so weapons (and ships) should pick from "some" effects. I may not be being entirely clear yet, but this isn't ALL just wishful talking... once I get the thing to actually compile I'm going to try stuff! Course, I may be biting off a lot more than I can chew... but maybe I can at least get us started.
A lot of the stuff inspiring me is already found in
fs2_open/code/ship/shipfx.cpp... take a look at the function "maybe_fireball_wipe"... down where there's options between normal and FS2_DEMO. See, there's stuff about number of particles, range, velocity, lifetime, size, and more. And the PARTICLE_SMOKE2 is hardcoded. Instead, imagine perhaps something like (pseudocode):
$Name: popcorn
$ParticleInfo:
+PCountMin: 40 ;; minimum particles spewed
+PCountMax: 80
+PRadiusMin: 0.5 ;; particle radius
+PRadiusMax: 3
+PVelMin: 0
+PVelMax: 100
+PLifeMin: 2
+PLifeMax: 10
+PAni: particlesmoke02 ;; particle ani
Obviously there's a lot to add, and a lot to think through (particularly in how the code actually implements this table, or picks which effect in the table to use). And in this case, in the code it currently relies on knowing the fighter's speed and size, which may be tricky to deal with if switching to tables... (maybe use these as multipliers?) But maybe you get the beginning glimmer of my idea?

Now if I can just
get compiling to work 