I've made up a few for a couple writing projects. One of them is a polytheistic (that's the one where you worship a bunch of gods right?) type that is practiced by a village (actually a few villages) of these "forest dwellers" who firmly believe that the modernization of the world is what caused most of the human race to be wiped out. The gods they worship are largely based off of old Norse gods, but there's also a few based off of book characters and works of art (I'm only saying that last one because I saw a few drawings/sculptures/etc. that inspired some of the gods.)
The "forest dweller's" counterparts who are trying to rebuild civilization go by a more spiritual belief. They still have one basic god, but they have a priestess that's kind of like a fortune teller. (she'll use tarot cards, crystal balls [although usually she won't], herbs, etc.) They believe that the spirits of the past manipulate their present and that they can help guide them through life. Also, they believe that fate is largely predetermined.
For this fantasy that I'm working on where people have the ability to change into an animal, pretty much every 'species' has it's own belief system. For example, the people who can change into birds believe that their god resides in the sky and has thus gifted them with the power of flight. But the three main branches of the 'bird society' (birds of prey of the day, birds of prey of the night and crows & ravens) have very different ways of believing how this came to be. The 'morning birds' believe that through the sun their god gifted them with flight, while the 'night birds' believe it was through the moon, etc.
Sometimes, I think I'm making things too complicated for myself, but I often have fun w/ making how a whole race's/societie's culture works.
