As odd as the author of this forum sounds, I have to agree that mods would be kinda nice. For example, I like dive bombing my bridges with the flying HAV. However, I seem to have troubles stabilizing due to the control scheme. A gyrocopter mod would be kind of nifty, so that I could more or less automatically stabilize. Not to mention that the gyrocoptor might have more than the 16 polygons the HAV does :P
Come to mention it, perhaps a high detail train mod would be nice? Some of us have high end machines, and we want to push them to the point where they scream out for mercy, shouting "Oh, please, no more polygons! I can only take so many! Mercy!"
Just a thought.