Galactic Scourge adds a mass driver turret. You can buy them, but they are also found on the Rebel Cruiser in GS.
I myself like the mass driver. It can do lots of damage, and its very effective against heavy warships, like Confed Frigates and Cruisers. However it only works well if you have 4 of them.
The Particle Beam is a pretty nice weapon, except it gussels fuel at an incredible rate.
The Neutron cannon is a decently powerful weapon, but its short range makes it hard to use. You've gotta be right on top of the enemy to use it.
I find no use for a tractor beam other than using it to destroy the alien cruiser. Because of its short range, it makes it extremely hard to use.
The cloaking device, while it gussels down fuel, is a useful device. You can quickly get up behind an enemy, decloak, shoot at it, then recloak. However, because it disables your shields when you cloak, it makes this maneuver not to effective against heavy warships.
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(This message has been edited by Captain Carnotaur (edited 07-29-2000).)