Ask HN: Looking for in-browser programming tutorials like 'Try Ruby!'

I'm trying to create a list of really good interactive, in-browser programming tutorials like 'Try Ruby!', but in other languages like Python, LISP, Scheme, Javascript, Erlang, etc. I don' know if they even exist, but if they're out there I'd like to locate them and create a nice web page for easy reference. So, if you know of any that are any good then please post them in a comment. Thanks!