You can also trade goods and items your colony produces with other players for a hefty profit. Such as nukes and whatnot. Probably one of the most fun ways to make money would be forming a nice pirate corporation and possibly band together in a fleet. Then terrorize players throughout the galaxy. And steal their money.
In addition, there is a ship in the game that has a special "weapon" which dumps a players money and goods if they're in range. So you can attempt to pick it up and flee before they get it back.
Note: Anyone who is playing, beware your warp fuel levels. If it drops to around 400 - 500, your best bet is to get somewhere safe and log off, or get some spice to jettison it. (This produces fuel in the game, you can produce up to 500 gallons of warp fuel per day with this method)