“ 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.”
“ The city was cursed many years ago. Since then it has not stopped raining. The gutters are inhabited by eels and the doors are on the first floor, coated with pitch. On a bad day, you can see the water level rise above the ground floor windows. Carts have both wheels and bladders filled with air to keep them afloat. And yet everyone is surprisingly dry.”
“ What a narrow street! The bowed windows of the upper floors encroach on the view of the bowed windows opposite, making it all very dark and shady down here in your carriage. You feel it slow down and stop, and there are raised voices outside. Craning your neck out of the door you see a smug cartsman ahead, whose cart is blocking just enough of the narrow street to make your passage impossible. He appears to be waiting for you to move, but your driver is hurling abuse at him and your horses are getting restless...”