Polylinguo

Polylinguo is the first web app to teach programmers their second, third, fourth (or higher!) programming language efficiently. Whether you're coming from a PHP background and want to explore Python, or you're an old school C programmer looking at Ruby, Polylinguo will help you quickly see how your new language compares to your old one, give you real-world exercises to complete your own way, and then compare your own way to the established best practices for your new language!