I'm tossing around an idea right now to put the fear of the unknown back into d&d.
The basic premise is that on the campaign world, the human settlements all cling to the coast of a vast continent. The players would all start as humans and would be a part of an expedition into the interior of the continent.
Along the way, they would meet and interact with the various other races of the campaign world, and their actions would partially determine how the different races treated humanity (disdain, scorn, friendship, trust, etc.)
When the campaign is over, move the timeline ahead a few hundred years and start a new campaign. This time, however, the players can see the affects of their character's actions far into the future. It would give them a real sense of ownership of the world.