Just watched Hacking Democracy again.. It started with the precinct in florida that the machines were rigged for Bush in 2000.. (total votes for Al Gore were -16,000).. They look into the machines and find out that the head of one of the biggest machine makers is a republican who promised bush the election in ohio in 2004..

They then found that some elections were fixed for the Republicans to lose(one election when you clicked on the republicans name the vote went to someone else).. In the 04 election they requested the voting receipts and were given copies printed 14 days after the election.. After going through the garbage they found the original receipts(which is against the law to throw away right away) and they didn't add up.. One of the original receipts showed 500 votes for Bush but on the new count he only had 211

It's a good movie and fair to both parties while going after the people who make the machines and the election offials themselves.. They have a website

http://www.blackboxvoting.org/

It's a fun watch before you go vote on one of the machines and with no paper trail there would be no proof..