Video tutorials welcome students to Treehouse Island, where they arrive in a zeppelin, meet a mysterious, eye-patch-wearing ambassador (see photo above) – think Mister Rodgers transposed to “Lost” — and unravel mysteries while learning to code in HTML, Ruby, Python, PHP and JavaScript. The service went live in November and offers three beginner-oriented learning tracks: Web design, Web development, and iPhone/iPad application creation.

In 2010, Web applications consultancy Envy Labs unveiled Rails for Zombies, an interactive Ruby on Rails teaching suite. Some 60,000 coders let the game eat their brains. Hoping to build on that success, the young company introduced Code School in March, targeting users who already know some programming but want to keep current with Ruby, HTML5, CSS3, CoffeeScript and jQuery. It plans to expand to an audience of new and younger users.