I thought up two (random) ideas for ships, and I thought I'd post the concept and see what you thought of them before I bothered trying to build anything.
Idea 1) Shield Ship: Most likely named "Aegis" or something. The idea is to have a non-player ship, perhaps around 50 meters or so, which projects a huge shield sphere, maybe around 200-300 meters wide. I haven't tested to see if Freespace can handle it or not, but maybe with multiple layers of shield too. (One at 300 meters, one at 200, one at 100, one protecting the ship itself, etc...) The ship be primarily focused on powering its shields, which would have a larger capacity and a quick recharge rate. This would have two functions: They could fly in close proxemity to capital ships, protecting vital areas from long-range bomb attacks. And if multiple layers are possible, flying your bomber up to the cap ship, launching your mega-bomb and having it explode in your face against the shield would not be fun. Also, it'd provide a screen for fighters, since they can fire out at the enemy, but the enemy can't fire back at them without first going within the shield.
Idea 2) Some kind of fast-sounding ship name, the idea is basically just a ship, preferably a large, well-armed ship, with an experimental drive that can be activated using *tab*. The drive would allow insane speeds, perhaps around 500+, but would not recharge its fuel supply. So there could be some tactical uses for a really fast, well-armed ship, but you'd have a limited amount of fuel available to pull whatever you need the speed for. Or maybe just use the idea for an interceptor that's capable of *really* fast menuevers in limited supply. You know, zoooom up to the incoming enemy, give them a pounding, and zoooom back out of there before they return the favor. It'd be a good interceptor if the job required keeping a single group away from the desired target, since they could get to the enemy quickly, expending most of their fuel, and attempt to do some damage before they get within range.