There are a couple I can think of.....
1) At large voting helps with state & congressional elections.
https://en.wikipedia.org/wiki/At-large
2) Weighted voting
https://en.wikipedia.org/wiki/Weighted_voting
But the Big Two are very much opposed to such systems.
It threatens their lock on power.
Interesting... Concerning weighted voting, I'm sure many people will oppose it as its almost seems unconstitutional and also depends on how the weight is distributed.