Keep in mind this before getting any big ideas, though:
It's scheduled for an august/september release and that looks pretty solid as at this point the entire expansion pack is already playable.
That means that a lot of super-complicated or difficult features are unlikely to be posted.
Here's a suggestion: A Jukebox option at the main menu to let you listen to any of the game's songs at will. If the song names are spoilerific, perhaps only unlock that after the expansion has been finished once?
