I don't think I've ever intentionally used the ball side of a ball-peen hammer like the illustration shows… and that was the kind of hammer I used for riveting (replacing sickle sections on sicklebar mowers and windrowers.)
One fun bench vise and hammer trick I learned during the U-joint job on my Thunderbird a few summers ago, back home on the farm where I can use either bench vise as long as I make the 200-mile trip: let's say you're trying to press something out of its bore, and you're putting as much pressure on it as you can get with the vise's screw lever and maybe even with a pipe over the vise's lever, but it's still not enough to make it move. Take the hammer and give the front face of the vise jaw a good whack, and it might just get the thing being pressed out to break free.

Hi gang,
I am going to be attending Retromobile in Paris this weekend and visiting Citroen's Conservatoire next week. If there are any specific cars you want close-up pictures of, let me know!