Output production and consumption statistics (The values from the "P" menu) for a given item to a signal
Providing the player with new tools or adjusting the game interface, without fundamentally changing gameplay.
Related to roboports and logistic robots.
Entities which interact with the circuit network.
With the code you've already made, I think it would be trivial to add combinators for other statistics like pollution.
I can't speak to the complexity of it; but this would be a hugely handy addition. Would be nice to keep on top of biter expansions.