Helma and RingoJS allow running JavaScript on the Java Virtual Machine by using Mozilla Rhino, with RingoJS being the successor to Helma; RingoJS provides features like CommonJS modules, full access to Java libraries, multithreaded programming using Workers without shared globals, and modules for tasks like HTTP, concurrency, and command line usage; examples are shown for calculating Fibonacci numbers across Workers and building a web server application using RingoJS and the stick framework.