Various codes:
Press www.freespace2.com first then type desired code.
~ + C player collision on/off
~ + SHIFT + C toggles countermeasures on all ships.
~ + K destroys your target.
~ + SHIFT + K destroys targeted subsystem
~ + ALT + SHIFT + K does ~10% damage to your target.
~ + ALT + K does ~10% damage to yourself.
~ + I toggles invulnerability.
~ + SHIFT + I toggles invulnerability on target.
~ + W gives the player infinite weapons.
~ + SHIFT + W gives all ships infinite weapons.
~ + 9 scrolls forwards through all secondary weapons
~ + SHIFT + 9 scrolls backwards through all secondary weapons
~ + 0 scrolls forwards through all primary weapons
~ + SHIFT + 0 scrolls backwards through all primary weapons