I Know i Suggested something similar via g-mail but maybe a cannon that can shot over blocks of your own ship so you can place it "inside" of a ship maybe with a very high rate of fire but low damage.
A Rail Gun
Now that the game has exteriors, weapons that sit on top of the ship instead of on the side are feasible. The only major issue is game balance -- would interior weapons like that be too hard to destroy?
well yea maybe but waht if they dont deal much damage that would counteract them or not?
It's actually less about whether interior weapons would be too powerful and more about whether they increase or decrease interesting choices when designing ships. For example, right now the player has to make interesting choices between adding weapons, shields, or armor to the outside of their ship, as well as where to place reactors/ammo such that they're close to the weapons without being too vulnerable. Low-powered interior weapons seem like they might actually make ship design less interesting.
So what I'm actually thinking of adding are very large, very expensive super weapons that use a lot of ammo/power and have really long cooldowns. These weapons are very easy to destroy, but can be placed on the inside of ships. Ships are likely to have only a few of these and will still need weapons on the outside, so they shouldn't reduce interesting decisions too much, and may even add interesting decisions (such as, should I surround my super-laser with several layers of armor?). They should also add interesting decisions when attacking a ship that has such interior super-weapons (should I take out the exterior weapons first, which are easier to kill, or go straight for that super-laser deep inside the ship?).
- Edited
hmm that are some good points maybe :
They could be expensive in money and if they have a high rate of fire you should keep in mind that you may need a ammo production unit and a reactor and maybe a crews bunk as close as possible to the weappone to keep it runing.
and maybe there could be a limit on how many you can build of these on a ship. (maybe 8?)
and they could also cause damage wehn they are destroyed.
but i would like to see both weappones in the game your idea and mine. 
Walt I like the idea of a interior superweapon, something that would require either a ship to specialize or be gigantic to make use of efficiently. I personally think something around 8x8 would ensure that you couldn't fit too many into your ship, especially with all the reactors/factories required to keep it going.
A possible way to expand on the exterior weapons is to make expansion 'modules' that extend inside of this ship and are the same size as the weapon itself (e.g Ion Beam module would be a 5x2) and you can attach it to a existing ion Beam to increase it's damage output by 25-50%.
Another way to improve on exterior weapons might be with enhancing the energy or ammo required to power it. Ammo could be produced, enhanced in another (different type) factory which increases it's damage by a set amount or maybe give it special properties like armor piercing/high explosive etc.
What about instead of direct connection to the sides, a indirect connection can also be made(Railgun extensions)?
H4zardZ1 thats a good idea!
Yep.
The extension itself, however, should be less wide than the actual cannon.
H4zardZ1 yea!
13 days later
I have and idea how small interior weapons could work. Make them have to be atleast 2 blocks away from the edge.