Telemaco is a simple chat program I wrote in Tcl/Tk to talk with my brother.
It works in a similar way to the unix talk program, that's you see what the other user
is typing in real time, when he presses the keys, deletes, and so on.
The shared blackboard allows the two users to draw to comunicate in an easy whay what
is hard to tell with words (i.e. the shape of something).
I think it may be an example of how cool Tcl/Tk is, in just 350 lines of code you have a GUI, the socket
stuff and a shared blackboard. The code is attached to this page, while this is a screenshot: