Ideas currently knocking around various groups I am a member of which some of these are still to be play tested.

SMALL TARGETS
Small targets such as jeeps and scout cars,-1 to be hit when they are moving.
This penalty would be applied to any small fast targets moving at over half their off road move.
This only applies to direct fire weapons such as antitank guns and vehicle weapons and not to infantry squads whose fire effects an area.

Low targets
Low targets such as Italian CVs, Polish tankettes and Bren carriers can count as obscured by low terrain features such as hedges. They are currently as easy to spot as a high sided truck.

SCHURZEN
Rapid fire makes no allowance for the use of this cunning invention at all. (i)A vehicle with schurzen should be allowed to make a saving throw against an attack by bazooka , or similar infantry anti tank weapon. This would apply to flank attacks only , a saving throw would be sucessful on a throw of 3 or more on a 1D6 .
or (ii)Firer ignores the usual bonus of firing against the flank with any of the above type of weapon.
Add either 10 pts or 5 pts to the cost of the vehicle

AIRCRAFT
Aircraft should be given either a flight path or called in against specific units. e.g tank force coming up the road or any units on hill x. A radio vehicle can be used to contact a plane and either change an order or order a strike against a specific unit.
Vehicles in woods cannot be seen by planes with the exception of artillery which choses to fire in the previous players turn.
Spotter aircraft and or forward air controllers are exempt.

GUNS
37mm hollow charge /steilgranat ; used from 1941 , not in massive numbers, it was harder to hit with as it was fitted over the end of the barrel - not breach loaded, but could penetrate 180mm at up to 300 metres, which is better than a Tiger 1 with 120mm at 100 metres . therefore i would give it a gun class 2 at short range only .
75mm short barreled IG from 1943, this was also issued with a hollow charge round , which is why the germans were using them on panzer 3's in 1943 - it was effective penetrating 100mm of armour at 100meters, which is the equal of a gun class 2. Make this a class 2 gun at short range only .

A/T rifles
A/T rifles can damage tanks with C armour values - but they can only inflict heavy damage - they cannot destroy (reflecting the lucky shot that knocks out the tracks etc. - but cannot be repeated..)

Grenades
AT grenades, these can be thrown against a moving vehicle hitting only on a 6. 1-2 no effect, 3-4 light damage, 5-6 heavy damage. AT grenades can imobilse a tank, but unless placed will not have full effect.

Communications
Heliographs/semephore here are some ideas from my friend Jon.
Communications. This is the trickiest, however it is important. I have worked on the following principles. Signals are transmitted on the following principles; personaly (messenger/runner), Semephore, Heliograph, telephone and radio. Semaphore/Heliographs are not covered in rapid fire so here is my take:- Semaphore/Heliographs needs line of sight. Often a chain between one end and another. Commonly in the situation of Forward observers they need to communicate via at least on other team to the battery. Each team consists of 2 (sender and reciver) and are the cost of gunners but cannot function as gunners. This can done quite quickly (within the turn), but the longer the chain, the more can go wrong. I rule as follows.