“ The PCs find a strange helmet, when donned it will take control of that PC and speak and act trough him/her. It explains that it is benevolent and needs their help in a quest and that it will stop possessing the PC when the task is done. Great if a player is gone for a number of sessions.”
“ What about a 'criminal' society with distinct laws - for stealing, the larger the value of something stolen, the less punishment the courageous thief recieves (but must return it of course). For this pirates(?) caught petty thieves deserve to be punished harshly. If you take, you better take a lot.”
“ A Deity of some sort has unleashed a plague of bookworms or something like that in the area. Almost all spellbooks are destroyed, along with bardic and historical books.”