“ 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.”
“ Mazetown stands right around the entrance to the Maze, and its whole economy depends on the people coming to visit the ever-changing and apparently sentient dungeon. They don't get all that many visitors, but the ones that do come tend to be rather generous in their spending; after all, if anything you take inside vanishes as soon as you go in, and everyone who manages to come out usually does so with fabulous treasures in tow, why not spend your coin on R&R before getting started?”
“ You come upon a ruined building in the back section of a city park (or other out of the way area of the city). The ruins are fairly overgrown. All that is really standing is a doorway and its frame. If you pass through the opened door, you travel to a different world. If the door closes, there may not be a doorway back to get you back.”