“ A continent is home to large, leathery flying beasts with a wingspan of over 70ft. Though shy, herbivorous and easily scared, it is possible that an enterprising person could domesticate them. They would be useless in war due to their timidity, but excellent if used for commercial air travel.”
“ <br />
The local band of 'nasties' (goblins / orcs / whatever) lives in relative peace with the local population.<br />
Along come the PCs and go through their usual heroic monster bashing routine, wiping out the nasties and pinching all their stuff, then continue on their way.<br />
Problem is, they don't kill ALL he nasties. The survivors want revenge and, after spending a few months recovering, start to take it in their own inimitable style (which is not unlike that of the PCs come to think of it).<br />
Next time the PCs are in the area they find themselves VERY unpopular with the townsfolk.”