Very imaginative, to say nothing of humorous markers. I'm tempted to try a few myself.
In the modern era, i follow the old McCoy rules for supply in which a unit has a standard 2-1/2/3-ton truck with four removable blocks made to look like boxes. When it engages in combat, one block, numbered 1-4, is removed each turn of combat. When the truck is empty, it turns around and heads for the nearest supply dump for another load, then returns to repeat the process.
Although designed for Moderns, this system would be easy to extend back to Horse and Musket armies using horse-drawn wagons.
For a WW2 tactical game I play (Men Under Fire) it's important to know whether a tank commander is spotting outside the turret cupola or is "hull-down" -- so to speak.
Many milk cartons these days in the US come with a plastic cap, under which is a safety seal -- a ring that pulls off a slightly concave cap (that looks a little like a shallow British Helmet Mk I). For the most part, my tank models have the commander exposed. When I need to mark him "down" I loop one of these seals -- suitably painted -- over the figure.
I like the idea of farm animals for designating unit status. Chickens for routed and sheep for shaken I can see, but pigs are very orderly and methodical. Wonder what I could use for WW2 in the Western Desert -- jerboas, gazelles and camels?
For Command Decision and Johnny Reb, I use the milk carton caps themselves -- suitably painted and with the unit designation on top -- to cover my order cubes (they used to be order chits but I glued the six most common order chits onto 1/2 inch [1.5 cm] wooden cubes).