what I would really like to see is a voting method that contains some steps for guaranteeing accuracy. Some feed back to the voter, while he/she is still in the booth about for whom s/he voted and if the ballot had a problem that needed to be corrected in order to be counted.
I think a pop-up window should do it: "You selected candidate Firstname Lastname. To cast your vote, press 'OK', to change your selection, press 'Change' ". The "Change" button then leads you back to the original menu of candidates.
To ensure that the output of the voting machine equals the input of the voter, I'd publish the software that drives the voting machine under an open-source license so everyone can review it for bugs and correct any bugs he might find. Publishing hardware documentation might help, too.
But in the end of the day, any
procedure for voting only establishes a probability, short of certainty, that one candidate has won. For all practical purposes, the the 2000 presidential election in Florida was a statistical draw, and no one can rule these out in the future. On the contrary -- the close races that cause statistical draws may well be getting more common as politicians get better at finding out what voters want and promising it to them. With that in mind, I think we need better laws to deal with statistical draws in elections.
Apropos paper trail: I have never seen a system that has all of the following three properties. 1) It leaves a comprehensive enough paper trail to document its own accuracy 2) keeps the vote secret, and 3) is more efficient than going back to paper and pencil. I don't think paper trails are the answer to buggy, and possibly fraudulent, voting machines.