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.
The spirit of a creature trapped in amber cannot escape to it’s afterlife / next incarnation / whatever.
Such trapped spirits can be contacted by those who know the right rituals and magical power derived from them – typically the power to control one individual of that species.
Can by quite powerful if the creature is a colony insect (ant, bee, wasp, etc) – simply control the queen and you command the whole colony.