Another source for sample ballots (albeit not as attractively presented as Slate) is the ACE Electoral Knowledge Network. The cool thing about the ACE archive is that it contains materials from the past 20 years and from many countries.
Andrew Reynolds at UNC has a nice selection of ballot papers (the Mongolian one on the right is from his site).
And to close, an example of the “monster” paper ballot in Florida 2012 that caused voters to wait in six hour lines. Turn the color intensity down on your monitor!