And one other thing, in response to wfaulk: surely the answer must be to attach paper printout gadgets to electronic voting machines, right?

Sadly, no. I was one of the big proponents of this idea until I saw the results of human subject experiments. The punch line: 63% of test voters failed to notice deliberately inserted errors on the summary screen. (And the test subjects just loved using our evil, lying machine!)

This is why I'm increasingly favoring the crypto solutions, which let you catch a machine as it's cheating.