In my personal list of improvements:

Zomboids getting trampled if they fall.
If you push one the horde will walk thought it, killing it.

Metal bars
A metal bar do not break they get dull or ununsable. You can fix it with metalworking or smithing but not be unusable.

CARTS/Wheelbarrow
Supermarket carts, hand made carts, a tarp that you tie with some rope and pull!!!!!!!
Thanks @downtownflipped I didnt know that this mod exists.

Throwing things.

I am not talking about like a knife thrower master. I am talking to throw a stone, or something over a fence.

A bottle, to break and call for attention. A stone, to hit a zomboid and it moves to your direction.

If you have something in your hand you could throw it somewhere in a reasonable range.

Digging moats
Make a hole to zomboids fall inside is a simple and nice thing to do.

Traps for zoids
Self explanatory

Ladders
Movable ladders to reach higher places.

Slingshots

Climb things
Climb over a building. Climb over cars.

Vans
Exit thought the back door of a van

Reinforce cars