The original butterfly ballot in the ill-fated Florida 2000 election was supposedly really confusing. Personally, I don't think it was that bad. Sure, I'd say that it probably shouldn't have been two pages with interleaved entries, but it isn't as if it was really all that much of a maze or anything.
The infamous Kevin Mullet came up with a much better treatment of the ballot. I thought that it might still be a little confusing because of all the white space, so I went out and tried my own version. It sort of worked, but in the end I think it suffers from having those negative space arrows. Friends and I were figuring that Kevin's treatment was still the best... However, I felt something wasn't quite right with the arrows so I ended up revamping it a little bit. I think having the arrows be the underscores to the items works better since people read down the page.
I sent those around to some more friends who thought that the whitespace was pretty heavy in my first version as well, and added some arrows to make the association more explicit. (I had tried a version where the gray background was just an arrow itself, but that also led to an aweful lot of jarring whitespace, even more so.)
Of course, nobody can really argue with the ultimate solution.
(Send me any additional versions!)