I tried this in rec and then moved it to travel - it's simple and effective - but depends on how many signals you want to communicate - all they have to do is count. and switch on/off.
When they look at me, I'll touch any number body parts - shoulder, elbow, hat - only one of them matters - say the hat - if they see me go to the hat, there is a signal 'on'. If they never see it - there is no signal on - they nod their heads and swing away.
Once the signal is on, they count the number of touches after it. 2 = bunt, 3 = fake bunt (that's our take sign) - doesn't matter where I touch, just how many touches. If I go less than 2 or more than 3, they swing away.
My fellow coach thought this would be too complicated for the rec players but they picked it up quickly - only thing to remember is 'on' and count.
I also use an 'off' switch - swipe across the leg sometimes.
I like this system too where you count touches to body parts - I find it flexible, easy to learn and almost undetectable because there is no clear pattern the other team can follow.
In my system, for the various strategies, a number of touches are associated with it. For example:
1 touch - drag
2 touches - slap
3 touches - steal and protect
4 touches - sac
5 touches - hit & run
I also use...
A key = it means that after I touch it, you start counting the # of time I touch any body part after. The ear could be the key. Anything I do before the key doesn't count. So players have to worry about seeing the key and then counting touches.
Wipe-off = a very useful signal I use that means anything I did before is off. We erase everything. Clean slate. This is great if a player looks confuse or lost and to mix the other team even more. Then you can give them a new signal or not (meaning they swing away in this case). A Wipe-off signal could be sliding my hand on my thigh for example.
Something else I like to use is a silent steal signal. I like to be able to tell the runner to go without having the batter worry about it (like in a 2-strike situation) or when I pick up a change-up grip for example from the pitcher. It is usually a body position that I have along with a specific gesture that I do like adjusting my sunglasses in subtle manner. The runner just glances at me and is gone if they see that silent steal sign.
Our 14U team uses a similar "code" to Steve. The "on" signal is when I touch the bill of my cap and my nose. I give a different signal for a play, for example rub my belly for a specific play, touch my shoulder then my wrist twice for a different play, drag hand across belly with a number of fingers out for a different play.
The girls have a lot of fun knowing the secret. It adds a whole new dimension to our offensive game.
This probably isn't relevant at early levels, but if a team is trying to steal your signals you can do a "first touch" indicator. Typically, someone has an indicator they use all the time whether they use a touch system (counting) or a more traditional system... they use the shoulder, wrist, hat, etc.
For teams that are adept at picking out the indicator, one way to get around it easy is to have a "first touch" indicator. That is, whatever body part I touch first in the sequence becomes the indicator the next time I touch it.
EXAMPLE: Let's say "bunt" is the belt. My signs go Wrist, Hat, Nose, Knee, Wrist, Belt, Hat, Chest. Because I started with my wrist, the next time I touch my wrist it becomes the indicator, so I follow that with the belt to give the bunt sign. Next pitch I still want bunt so I go Nose, Hat, Wrist, Leg, Wrist, Nose, Belt, Hat. The nose became the indicator that time.
This works with a touch system, too... as long as you either 1) stop after the amount of touches you want or 2) have a "close" indicator to complete the sign.