I made this logo for my secondary high school, and it was actually the first paid assignment I did. It happened rather innocent, as I was bored in class scribbling in my notebook and the teacher noticed the logo. He told me to further elaborate it and hand it in to the school council. I did, and it earned me a pretty nice buck.
The logo is still in use now since 2010. It's pretty amazing to see your creation on a 6 square meter billboard.
Check out the site: http://www.zsc.nl/