Tachyon: The Fringe Cheats

Boost speed to maxiumium using the afterburner, then hold down 'Q' (the slide key) then let go of the afterburner to continue in the same direction at the same speed without draining power. Note: This disrupts the game flow, as many missions can easily be accomplished without fighting.

When using the RAGTAG cheat, before launching, sell the 4 most expensive ships (IE all but Orion) and when you hit back, they'll reappear, but you'll still have the money from selling them.