How often do you get to 404 pages? Usually, they are not styled and stay default. Recently I’ve found test.do.am which interactive character attracts attention and livens up the error page.

Probably, there was just a cat picture, then they thought up eyes movement and developer implemented the idea.Now user visits the page and checks out the effect. It’s cool and pleasant small feature, it catches, then user discusses it with colleagues or friends and even repeats the feature. It could be this easy, if not: