Easy Kills
Hold down "Shift" and type "dynomite" (without the quotes) while in the cockpit to enter Debug mode. Target an enemy and press "Ctrl" and "F12" to instantly destroy the enemy. In higher difficulty settings, you might have to press the combination twice -- once to disable the enemy's shield, and a second time to blow it up. You will not get credit for the kill.
Invulnerability
Hold down "Shift" and type "dynomite" (without the quotes) while in the cockpit to enter Debug mode. Press "Ctrl" and "I" to make your ship invulnerable to damage from all types of guns, missiles and other attacks.
Self-Destruct
Hold down "Shift" and type "dynomite" (without the quotes) while in the cockpit to enter Debug mode. Press "Ctrl" and "K" to destroy your own ship.
Collision-Free
Hold down "Shift" and type "dynomite" (without the quotes) while in the cockpit to enter Debug mode. Press "Ctrl" and "C" to give your ship invulnerability to enemy attacks, as well as the ability to pass through projectiles and ships without taking any damage.
Targeting System
Hold down "Shift" and type "goodtarget" (without the quotes) during spaceflight to change the targeting system in the cockpit to more closely resemble the targeting system used in turrets.
More Ships
Type "alswantsmoreships" (without the quotes) at the simulator mission select screen and follow the on-screen prompts to fly enemy ships, including the Dralthi, Vaktoth, Devil Ray and both types of Mantas and Morays, in simulated missions. Press "Z" to toggle the ships.
Music
Hold down "Shift" and type "moretunes" (without the quotes) while in the cockpit, which turns on a radio that lets you tune to individual pieces of music from the game's soundtrack, including orchestral music and songs from the band Cobalt 60.