Starting off? A multiverse with individual universe separated from each other by the walls of space-time. I'll make multiple worlds, including:
-Equestria
-A 'nicer' Earth with certain aspects in history altered (Firefly isn't canceled, the Library of Alexandria didn't get burnt down, Native Americans are immune to Eurasian diseases, etc.)
-An Earth where the holocaust never happened, and just that.
-An Earth where Alexander II of Russia did NOT get assassinated.
-Various combination of several possibilities.
-A mini-multiverse where different cartoon universes are branched together via wormhole
-The Star Wars universe, except that any Dark Jedi are unable to use the force without having their nervous system shut down, Gungans or Ewoks are nonexistent, and Midi-Chlorians are utter tripe.
-The Westpall Universe. [http://knowyourmeme.com/memes/tommy-westphalls-universe]