Here's a thought on voting systems: suppose for the sake of simplicity that all of politics actually falls on a one-dimensional line, and there are three clusters of people, A, B, and C. Think "republicans" for A, "democrats" for B, and "green party" or "reform party" for C. Say their adherents number something like 45% A, 40% B, 15% C. If everyone votes their conscience, A wins, and if the Cs accede to the treehouse-of-horror aliens laughing at their thrown-away votes vote according to their A/B preference, then B wins 55% to 45%. This is all well and good and understood even by people that haven't heard of Arrow's Theorem, but is there anything we can do about it short of changing the statutory and consitutional election law?
It seems like all the B-ists and C-ians ought to get together and form a pact (without necessarily merging their parties!) that on the night before the election, they'll determine as best they can what the current polling numbers are, and if everyone voting B and C separately won't give the election to A, then they'll tell everyone to vote B or C as they see fit. Otherwise, they'll advise everyone to vote for whomever of B or C enjoys the most support within the coalition. Of course there are plenty of problems. If there's a tight three-way race between A, B, and C, then fudging of vote estimates and defection of coalition members are real threats. Also it's absolutely in A-ites' best interest to join the rolls of the B-C conglom as double-agents, because they'll make it that much more likely that the vote will be split.
But surely some economist already thought about this and figured out a solution? Maybe?