A place where a fertility spell has gone wrong.Kisses can lead to pregnancy, any fungus infection runs rampant, corn grows as soon as it is planted,ect.
A place where for those who sleep in it,the real life and dream world is blurred-so nightmares can be deadly.
The PC's end up in a strange world where the very rocks are made of gold and jewels.As such gold and jewels is worth very little, but the iron in their swords and belt buckles is suddenly worth a LOT.
A cave full of what appears to be gold nuggets-the nuggets are in fact radioactive and will poison whoever takes them.
A place where scratching an itch is seen as highly rude.The problem is, it's full of biting insects.
There is a place where there are living dinosaurs but in miniture.So there are foot long Tyranosaurus Rex's and four foot long Brontosauruses, for example.
A Cloak of Shadows that causes mushrooms to grow in its own shadow. A crouching theif might find himself in a ring of poisonous toadstools, an interesting thing for a sentry to find after the thief has left hiding place.