Whichipedia is a site which asks a simple question: "Which Wikipedia page is longer?" It presents two choices, so you have a 50/50 chance of getting it right, simple fun. But, the site also records how many questions you get in a row so now there is a competitive element to it.
Suddenly there is real thought going into if the Wiki page for 'List of special routes of the United States Numbered Highway System' is longer than that for 'Manga outside Japan' (it is) or if the 'Poker Hall of Fame' page is longer than that of 'Adaptive management' (it isn't).
Honestly, this page is a time thief, I'm suddenly asking questions about the '1976 Canada Cup' and the 'List of shipwrecks in Febuary 1942'. Click on the image below to give it a go.