This week's book giveaway is in the OCPJP forum. We're giving away four copies of OCA/OCP Java SE 7 Programmer I & II Study Guide and have Kathy Sierra & Bert Bates on-line! See this thread for details.
java.lang.Runtime.exec() You can use this to call external programs, or pretty much do anything you would do from the command line. So to start a new Java program, you could call "java -classpath... mypackage.MyClass"