If you were mentoring someone who is pretty new in java, you would surely tell them about JUnit and your favorite mocking framework and the language grammar. However, you know that Java is a culture and a history and a spoken language as much as a written language. You would start talking about jakarta, or tomcat, or a DI, or a bean, or a war file, or eclipse workspaces and your apprentice would scratch his head and stammer. The truth of the matter is that the grammar isn't but 10% of what java programmers know.
Which projects would you have your student study in order to soak up the rich history, culture, and language of the java programmer? What are Java's greatest hits and misses?