I'd like a world with no major gods of agriculture, the sun, etc. Instead, people worship heroes. The big time generals and conqueror kings actually ascend to heaven and grant spells to their priests. If a culture is destroyed, its gods are forgotten and go away.
This would give a very good reason for adventurers to exist. If they become famous enough, they could literally become gods. Not to mention minor gods that maybe saved a village. They could become demigods, even if their power only extended to that small area.
Not sure how this would work in actual play, but I think it might be worth working on.