Well, here's an idea for you:
Whenever someone shoots down a friendly plane, he will only be able to fly the C202 for 2 hours! MUAHAHA.
Another idea would be to disable the killshooter and code in a "bastard" check: If you shoot down 2 friendly planes in one hour you will only be allowed to fly the 202 for 2 hours... continous killing of friendly planes (say, 5 planes in one week) will get your account cancelled. Works for the 2 week trialers and for those who spoil the game and SHOULD be kicked out no matter if they pay $30 a month.. its better to kick out those morons than to lose 10 or 12 accounts because of that person.
What say ye HT?