“ The PCs are accosted in a major city containing at least one famous fortuneteller / prophet of the future. They are informed that their as-yet-unborn child will (insert terrible evil), and that, although they are very sorry, the PC must be executed to keep this from happening.”
“ Consider the idea of spontaneous genesis of life, as used to be belived. What strange kinds of life might arise from modern substances? What kind of vermin would a landfill produce, or an oil spill on the ocean?”
“ The heroes find the crumbling, overgrown ruins of what appears to be some sort of grand dining hall in the forest. Deciding that it is a good place to camp, the set up a fire in the center. However, they are woken in the night to see skeletons waltzing in the moonlight to organ music that emanates from the open air. The skeletons touch nobody, dancing around them all night.”