Interesting article about how crowdsourcing is defined by Josh Catone. In the article, crowdsourcing is broken down into three categories. All of which are shown with websites that are used as examples.
Personally I don't think I've ever looked up a health topic on Wikipedia; I use WebMD for that. Which isn't crowdsourced, I don't think -- I think they pay people to write the content on WebMD. Still, nice idea to offer college credit!