After reading about Wikipedia in Wired magazine, I started showing it to students during my classes on website development. At that time, September 2004, all you needed to do was create an account and you could instantly add new articles. In one class, I created the Tillsonburg page, a Canadian town near where I grew up.
I just created a new article on hidden lines. I was surprised that such an elementary concept of geometry did not already have its own page. It was an interesting exercise researching other related material to use in the article. There were geometry articles, of course, and a computer related article.