There is a HBO documentary called Hacking Democracy which documents the crusade of Beverly Harris and associates to expose the issues with the American electronic voting system. And I just finished watching it on Google Video, but is also available as a Torrent.
There are several brands and type of electronic voting machine in the US. In the UK we still use hand counting and paper based voting because it is a known proven technology, but the electronic systems in the US are essentially black boxes. The voter approaches the machine, puts in their vote and then nobody knows what happens until the central tabulator declares a winner. It is even illegal to have a look into how the system works. To me this stinks because I don't understand how something that is unnecessarily secret, can be trusted. The voter's vote should be secret, but certainly not the counting process.
Anyway the documentary exposes several critical flaws in the electronic voting systems that would allow real-world vote tampering without detection and yet nobody in control seems to be concerned by this. To me voting systems should always be in a regular state of review, but this documentary shows officials actually showing distrust towards an open discussion of the process.
And another thing. Don't be put off by the opening line of the documentary "America, the world's greatest democracy" everybody knows that America isn't a true democracy so that statement is like saying that a Double Decker Bus is the greatest Car ever made.