What's the point of the little ball on the end of antennas?

No, it really does serve an electrical purpose.

It's called a "corona ball." The idea is to avoid having any sort of a sharp point or edge on the end of the antenna. A sharp point would produce more static as the car moves through the air.

...later:

A bit more explanation: The car builds up a static charge as it moves (from friction of tires against ground, among other things) and this charge is going to leave the car one way or another. A sharp point or even edge encourages the charge to leave via that route. (This is a principle discovered by Benjamin Franklin.) And if the charge leaves the car via your antenna, the resulting static noise is coupled directly into your radio's tuner. You obviously don't want that. A sphere - no sharp edges - is the best way to discourage the charge from leaving through the antenna.

Yes Sullivan, If i break the ball off of the top of an antenna i do get static but i never had it explained.

And on manual antennas something to grab on to to push and pull

they serve no purpose except to prevent the antenna from stabbing someone.

.

Primarily to prevent injuries. It's too small to have any capacitive "High Hat" effect.

So you don't get stabbed

so there is no sharp edge