“ On a location with numerous webs, and at least one big spider, there is a something inside a cocoon. It is humanoid in shape, still moving. If the heroes free it (not before they kill or drive away the spiders), they meet a ... zombie!
The poor zombie wandered the dungeon alone, and tried to kill a big living creature (= a spider). The spider used the usual treatment, even if this victim did not look tasty. The zombie can be easily killed as any other zombie. It got but several doses of spider-poison, so can be something worth if it is extracted. You can mention to a druid or ranger the fact the spider had no poison anymore.”
“ A continent is home to large, leathery flying beasts with a wingspan of over 70ft. Though shy, herbivorous and easily scared, it is possible that an enterprising person could domesticate them. They would be useless in war due to their timidity, but excellent if used for commercial air travel.”
“ An intelligent mask that, when worn, takes control of the individual and mimics their personality, only to commit horrendous crimes and commit great acts of evil in secret.”