My suggestions:
Being able to buy turrets, beds and lots of stuff for decoration and functional
Re-tweak the car (A little too slow and too "stiff")
Improved Graphics! (I know that this is a unfinished version, but it'd be nice if this was made!)
More guns
Attachments to guns (can be brought and equipped to the gun)
Real clouds
Food for the character!
Bullet casing ejection
When can i know that the next version will be out?
I'm dying for the new version.
My suggestions:
Re-tweak the collision (You hit the enemy with your plane, you get lots of damage but they are unscathed!)
Refinement of earning system (Every downed enemies will be 50+ AP. Either that and/or cheaper planes.)
Shop system (I found out that after you buy a rocket, it's just for a day!)
Altimeter (Self explanatory)
Campaigns (Like what celo753 said)
Co-op missions (Team up with people and eliminate large groups of NPC planes and rewards are divided evenly)
The game is good in it's current state, but adding suggestions will make some people and the suggester happy. Hope i didn't make anyone mad.
My suggestions:
Altimeter
More weapons (Hellfire, Hydra and MG)
More kinds of mission (it's kinda boring playing search and destroy all the time)
More enemies (put Jeeps, Helicopters and allied units)
More Helicopters (RAH-66,AH-1 and the like)
Newer or bigger terrain
Easier control of the Helicopter
That's all, for now.