It also had an accidentally-fun feature in its hyperlinking system. Hyperlinks were intended to be used to be used for words that had their own articles, but you could link to any article, and when you hovered your mouse over the link the name of the target article would pop up. This could be used to make the closest thing I've seen to an English equivalent of Japanese furigana puns. I'm having trouble finding a good example right now, sadly.