I would love to see a networked 'challenge mode'.
Unlimited balls, first to hit the left orbit gets a point, first to hit the right ramp, first to hit a target a certain amount of times, first to start multiball, first to a certain score.......you get the idea.
You could play against anyone or more importantly someone you know. I would prefer to see networks used for challenges rather than just high scores.
Sorry if this isn't really an innovation. 
I agree, this comes down to idea of different rule set available and pinball having more than set of rules you can choose for different types of game play, IMO people would pay for new rules and use of servers for online gaming, it's potentially another money maker and good for company cash flow between titles, it may not be the case of who gets the highest scores with 3 balls, it could be who can hit which ramp the fastest, which can help with your skills on the game
