Inspired by xkcd, I sat down and read through the Wikipedia page List of common misconceptions. Divided into multiple categories such as sport, chemistry and cooking, the article list common misconceptions, such as Thomas Edison inventing the light bulb and humans and dinosaurs having co-existed.
It is surely a recommended read – either go the whole way through or choose your favorite category. This is one of the limited number of Wikipedia articles with Pending Changes Protection, meaning each edit is checked through quite carefully to avoid any mistakes appearing, before it is accepted. All facts are thoroughly sourced.