How to steal an election by hacking the vote
Ars Tecnica have published an excellent, very approachable introductory guide to the massive flaws with DRE type e-voting machines. Includes illustrations and a solid set of links for further reading. (Thank you to John Hornbaker for bringing this to my attention)
Avi Rubin's blog
This is an overdue link, Dr Avi Rubin's blog is full of good sense, as would be expected.
A Brief Illustrated History of Voting
It's brief, and it's illustrated. The ever-wise Doug Jones has written this wonderful short history of voting's evolution from clay shards to e-voting.