Extra Money
You can perform a hex edit (using an editor available online) to provide your Global Treasury with an influx of cash. To do so, complete the following process.
Open a *.SAV game file in the hex editor
Go to block: 7414
Type in 1388 (which should appear as 13 88 in the editor)
Save the file
Reload the file in-game and look for your increase on the "Planets" screen
Additional codes are available that provide additional money, including a hex value of 5F5E1 that will yield $1,072,735.
Killer Exploit
With some careful preparation, you can produce a situation where your enemy is helpless against your attacks. First, build a ship that has a single missile equipped (make sure that you're not equipping torpedoes or scatter packs, as those don't count). As an extra, equip something like the Neutron Stream Projector that can disable armor. As for general ship specs, make sure that your ship is both fast and tough. Once you engage in combat with your sleek new ship, disable your missiles and get close to an enemy ship, until you are within two spaces. Now, fire your weapons at the enemy group, then select the "Wait" option. Provided you survive any retaliation, you'll get another turn. You should still have access to any extra weapons, which you can use again. Then wait, then fire your extra weapon, then wait, then fire the extra weapon, and so forth. Repeating the process prevents the enemy from being able to fire, and you can keep the chain going until you finally win.
100 credits...