Inspired by the "crew of one" challenge, and specifically by Jive 320's comments, here's some challenges for you expert players to liven up the game a bit.
Game completion challenges - that is, accept this challenge and play the entire game while following it.
Fair Fight challenge - no upgrading your ship. Use the same base model that all the AI get, and nothing more. You can buy all the ammo you want, but no extra cannons/turrets, no additional/swapped weaponry or armor, etc.
Close Combat challenge - no ranged weapons; use only Emalgha cannons/turrets for your base weaponry. Mines/defense pods can be used, unless you're feeling really hardcore.
Sniper challenge - no turrets (including swivels) and no guided weapons - cannons, bombs, and unguided rockets only.
Mismatch challenge - No neutron/blaze/Emalgha weapons (phase only) in Voinian space, no neutron/blaze/phase guns (Emalgha only) in the rest of the galaxy.
Millenium Falcon challenge - use a souped-up freighter for everything. (Specifically, the valid ships are: shuttle, UE freighter, UE transporter, any Miranu freighter, Emalgha freighter, or Voinian freighter. Freight-courier, helian, scoutship, and arada are not permitted.)
Make Every Shot Count challenge - if a weapon has unlimited ammo, you can't use it. (If you're feeling extra virtuous, you might also refuse to equip Needle missiles.)
Bomberman challenge - space mines and defense pods only; no cannons, turrets, or anything with its own guidance/propulsion.
--------------------------------------------------------
Special-purpose challenges - things to do apart from completing the game.
Profit Margin challenge - What is the most net profit you can make from a single cargo haul? (Escorts are permitted, but you must count their hiring costs and your fuel as expenses.)
Excessive Upgrade challenge - How many different outfits can you (legally) equip a ship with? Launchers and ammo both count, as does anything else which appears in your info window. (Thus, maps and fake IDs don't count.)
Most Wanted challenge - Can you manage to achieve a rating of Criminal or worse with every inhabited system in the galaxy? No dominating stellars, though - that's too easy a way to earn hatred. 
Role Model challenge - Can you achieve a rating of Upstanding Citizen or better with every inhabited system? (Harder than the Most Wanted challenge, I should think.)
------------------
.xrrt n re'hbl ,fvug qnre anp hbl sV
(This message has been edited by Jynnan Tonnyx (edited 06-19-2001).)