Baseball zombies at the parks/ranges, a zoo where zombie monkeys throw rocks at us. Zombies themselves could weakly throw rocks, like 2-5 spaces for 2-5 damage if they are walking over them, takes turns. Zombie hulks or whatever could throw vehicles a little distance and damage them, don’t try hiding behind one. Brutes could throw furniture, smashing it in the process.
Could even have mitts equippable that are basically slings i.e. use baseballs to fire and are wielded.
Maybe have “grey goo” type bots that if they run into scrap piles, could start building robots or throw scrap, otherwise harmless, though the waves of robots that could be generated would be annoying. Maybe each one they make is ‘made from’ themselves, like promethians, with each child having half the hp of the original. Are there mud creatures in the game? Could give an incentive to clearing swamps.