1. Get rid of Congressional districts. They are arbitrary and too easily fiddled with. Instead each state has statewide "at large" elections for its members.
2. Get rid of winner take all elections for the House. When a member is seated in the House, he gets the same number of votes as the number of people that voted for him. Since each state election is "at large" and state-wide, some candidates will not "make the cut". Candidates that did not "make the cut" can give their votes to a candidate who will be seated in the House. This has the effect of making every vote count which should do wonders for voter participation.
3. Get rid of the electoral college. The President is the person with the most votes. This will get rid of that annoying practice of ignoring voters in all but the few swing states.
4. Get rid of the Senate. We don't need two legislative bodies. Its function to represent the interests of small states doesn't mean so much anymore now that we have become more of a single nation rather than a union of sovereign states (Like it or not, that is what we are and we aren't going backwards).
It occurred to me that the reason that moneyed interests can have such a big effect is that they only have to buy a few key people in order to get their way. Less than 50 contests can turn the whole country around. They can do this because of the winner take all system. If you win by one vote, you will everything which means that wealthy donors can target a few key elections and make a big impact.
So, I think that if we just get rid of the winner take all system and instead for to a system where every vote counts will will revolutionize our politics in ways that reduce the influence of big money and increase voter participation in the process.