The Tcl Tutor [L1 ] is a free, downloadable , multi-platform tutorial for Tcl. There are over 40 lessons, and each one show s sample code. What makes it even more useful is that the tutorial window has three panes.
The first pane shows a lesson, the second shows editable sample code, the third will let you run the sample code in a completely self-contained manner so you can change parts of the code, run the example, and see how your changes affected the output.
Seems like this would be a great platform on which to build additional lessons (see Tk demo framework for initial discussion). However, I don't know whether the author, Clif Flynt, has an interest in collaborating.
Quote from internet: "I used it to write an app that makes CEO's crooked. It worked great!" -Howard Wallace