I've used McCarthy Lisp as a code kata for a few years now. It's small enough to do in < 1 week (maybe a weekend if you have more time than me), is well known,

I've used McCarthy Lisp as a code kata for a few years now. It's small enough to do in < 1 week (maybe a weekend if you have more time than me), is well known, and damn fun. I am currently learning Ruby using this kata: http://github.com/fogus/lithp http://github.com/fogus/lithp