SNAP! (Build Your Own Blocks).
We’ve had great fun, and results, teaching kids to program with Scratch. Now, Berkeley has “an extended reimplementation of Scratch … that allows you to Build Your Own Blocks. It also features first class lists, first class procedures, and continuations. These added capabilities make it suitable for a serious introduction to computer science for high school or college students.”
I’ve only played with it a little - but getting started with Snap! is even easier than Scratch - because it’s browser-based (i.e. written in Javascript and designed to run in the browser).
You can try it right away and it’s worth it - even if you’re not a kid.
