There are also animist gods, gods more akin to what we'd call spirits.
In a book by Greg Keyes I just read (the waterborn, from the serie Children of the Changeling) there are two main types of gods : gods of places whose power lies mostly in their realm (which can be any size from a pond to a whole "country" - basically 3 months horseriding); and gods of things, who are the spirit of whatever they're contained into.
Some can manifest themselves wherever they want, while others can or have to be summoned. Some are vessel to other gods, others were made from another more powerful god and as such are a sort of extended conscience of them...
This differ greatly from the Black and White model, and I hope we can one day randomize all that, because it would just be great to be surprised each time. Am I the only one to think that gods being just an ultra tough creature is lame ?
And let's say you kill it, what happens ? If that god's followers were using their god's power as a source of magic, can they still do that ? Does this god's power seek another imbodiment and take refuge in you ? Does it leave an empty position in the universe, waiting for someone to take it ?
If you ever become a god, what does this imply ? Will time go on a different scale, will you need to sleep for hundreds of years before doing anything ? Will you still be able to protect the ones you cared for as a mortal ? Will you even be able to recognize them, or is it more akin to watching ants from afar ? Will you even remember who you were as a mortal or quickly forget what your former life was ?
Can gods be reborn in the next baby that comes to this world, or does that baby need a ritual ?
And what if you didn't challenge a god but side with him and have his avatar as a "companion" ?
Did gods in your world establish rules that forbid them to directly enter human matters, or other god's matters ? If they have laws, how do they enforce them ?
What do they need ? Do they rely on sacrifices, another god's existence, some concept (for example the god of war growing stronger and stronger as mortals conquer each other) ? Is there a cyclic rise and fall of their power ?
How do they consider mortals ? Are they cattle, their creations, a result from a past error, toys, equals ? Can gods have children with mortals ?
Where do they come from ? Have they always been there, have they created the world, are they mortals who ascended into godhood ? Can they age, grow weak, do they need to do something else to counteract that ?
What is death for a god ? If the god of fire dies, will fire go extinct, the sun darken and the summer get cold ? Or at the contrary will fire go wild without any god to control it ?
Do gods believe in something ? Are they omniscient, or can mortals or other gods hide something from them ? Is there some sort of higher god that none of them has seen but at their birth ?
Now just mix and match and you'll have a tremendous amount of Fun. Just remember : for anything to be interesting, gods must have needs and goals. Some gods could very well satisfy themselves with maintaining the equilibrium of the world, but there need to be others throwing it off balance then.