Online Ruby

[Paddy]

That reminds me of TclTutor:
  http://www.msen.com/~clif/TclTutorTour.html

TclTutor is a great Tk application that teaches Tcl/Tk by having all
the lessons and examples set up waiting in the app. The examples can be
edited/fixed and re-executed.

I still bring up TclTutor when I delve into Tcl programming (after
several years), it is invaluable.

I guess a Python equivalent would be Idle, pre-packaged with lessons
and examples from the Python tutorial available from the Idle menus.

- Pad.