I was suprised as to how much info you can find for my state's board of elections website. You need your name and your birthdate, at least, to get the record. Although it doesn't say who you voted for, the record does have revealing info like your address, country that they registered, and the party you're affiliated. I'm still suprised as to how easy it is to find info. I just performed an experiment to see if my peers actually voted.
My peers are in another social network website (not MySpace). During last year's election, the network site decided to allow users to start and join groups groups for particular (practical and non-practical) causes like global warming, the war in Iraq, "Jon Stewart/Stephen Colbert for 2008,etc. I admit that I joined in a few groups during that time, but I deleted them three weeks later (before Election Day). Here's the blackmail: My peers joined so many of these internet Election Day Groups and some of them never voted. Shows you that all they do is brag and that they didn't do anything. They post their birthdays on the network, so I was able to look up their records easily.
OK, I admit I did some stalking. But if I can find voter history info for my state, that means anyone can.