Urth Digest, Vol 51, Issue 18
In response to the comments on it not being a good idea that everyone should vote, this was a main premise in Heinlein's Starship Troopers. In that society, you weren't considered a citizen (and thus allowed to vote) unless you had served a tour in the military. It wasn't mandatory that you served (like in certain contemporary European countries), but you weren't allowed to vote-- you weren't considered to have "earned the right"-- unless you had served. This was a primary motivation (if I recall correctly) of the main character joining up. I'm not sure how much of this was kept in the movie . . .
-Steve