Well, the method of making sure nobody's looking over your shoulder at the physical ballot box isn't exactly all that high-tech a solution either... postal votes aren't above being tampered with, and there's no way to tell that it was genuinely marked by the voter without coercion either. I can answer the simpler concerns like print screen, of simply never actually showing the vote on-screen...

But votes by Internet seem inherently more insecure to me as well, and I'm supposed to know the ins and outs of making things like this secure... I can't imagine anyone actually doing it because people still have the idea that anything that's on the Internet is just floating there out in the open waiting for someone to pluck it out of the airwaves and run off with it.