Well, CDs are really useful in Combat, specially against Spammers!
- Against Mines, Missiles, Torpedos: When your opponent fires one of these, fire a CD right away. If you're fast enough you'll blow the Mine/Missile in their face, so the one who fires them is the one that gets damage, not you!
- Against Larger Ships that try to EK-Turn: CD knocks the ship out of Engine-Kill, so, when fighting a Gunboat in a Bomber, and the Gunboat tries to Engine-kill and turn, you can fire a CD Mid-turn so it'll get kicked out of EK and won't be able to turn completely.
- When you cba to hit someone with Guns(!): Let's say You're fighting an Eagle in your Roc, and you've CDed one of his Mines and one of his missiles, so he's flying around with a silver of hull left... Ever noticed CD does some Hull Damage? This will work best if you're using Mosquito. Take the shield out and fire a CD or two. The Eagle will go Boom!:P
Other than these, the only other usage of CD that I know is what it's named after: Cruise Disruptor.