Scratch - Create stories, games and animations
Code Combat - Learn to code by playing a medieval warrior game. Students can play the basic elements of the game without signing up.
App Inventor - Cloud based interface, from MIT, which assists with the creation of basic mobile apps. Created apps can be uploaded to the community gallery for download to phones. Plenty of tutorials about how to use the program and how to implement the use of the program in class.
Code Avengers - Learn to code HTML, CSS, and Javascript with lessons on coding followed by coding tasks and challenges which are components of creating a website or app.