A rumour of the knights of some powerful king that sleep until danger threatens the kingdom.
The truth is that they were rebels, trying to split the kingdom. Once captured they were put into an enchanted sleep, protected from age and harm, until their aims have been carried out by others in which case they will awaken.
There is a loophole in the spell in that trying to take one of their weapons will also awaken them.
A dragon who demands to be told stories, if the person cannot comply, he or she becomes a meal for the dragon.
If a ghost possesses someone that had a different personality to them in life, the possessed body will slowly rot.
An Orc tribe that is relativly *gentle* instead of warlike.
A demon that feeds on good feelings, causing those around to feel upset or angry all the time.
Stinging nettles with a deadly sting that kills within minutes if the person who is stung cannot be healed.
A demon in human shape that murders travellers, however, he can only travel a certain distance from his home.One the adventures have passed that point, he is no threat to them.
There is a certain kind of silver-coloured spider who's bite injects an addictive drug into the person that creates a sense of euphoria. Once bitten the PC has a 50% chance of being addicted to the spider's bite and will carry it around with him or her.Long term use leads to serious injury or death.At first the PC will just seem a bit slower or sleepier then normal.
The secret for immortality has been discovered by an eccentric wizard/mad scientist. Its found you need to reapply once a month. As people stop dying, and the birth rate increases exponentially, people are forced into homelessness, because of the need for food reamins the same, and food is not being produced fast enough to feed the undying population. The PCs have to find the creator and kill him, and destroy production, to save the world from undying, unending torture from hungryness.