Here is another thing I'd like to see: Maurading Pirates. That do...pirate stuff.
How about a 'minor race' of sorts that was pirates. They could run a protection racket against you (or other civs), for them to 'protect' your trade routes. ("Gosh, wouldn't it be a shame if your trade routes were set on by pirates? I hear they're pretty bad in this sector...let me do you a favor. For three easy payments of 250BC, I'll see to it that those nasty pirates don't bother you.")
They could have a planet to base thier operations out of, but with the ability to evacuate the planet if a civ comes after them in force. Or maybe just have them spring up again, like the cat that wouldn't go away.
How about pirates that spring up from the criminal element of an unhappy planet? A sort of insurgency...maybe a terribly unhappy planet would just become a pirate planet, a splinter off your own empire. Of course, this would require the uber-leader to send in 'pacification' troops to re-take the planet by force.
Woohoo! Pacification troops!
Anyway, I'd like to see pirates be more than what they are now. Maybe it would help if they didn't have a galactic range requirement so they could maurade and pillage anywhere they please rather than just sitting in some corner of the galaxy just waiting to be shot up by someone.