@|eragon|: create a new var (for exaple add "var mSpeed") and add it to your Missile-class. now, add "mSpeed = -40;" to your onLoad()-function, change in your onEnterFrame()-function: "_x += speed + mSpeed;" and add "mSpeed += ..." to your onEnterFrame()-function.
@btownballer2k5: i think you mean put "resetHealth();" in your onLoad() function (class Ship) (in your onEnterFrame() function, your health would be 100 all the time!)