I teach a lot of programming classes (mostly Ruby and Python), and it never ceases to surprise me to discover how many people are still working in Tcl. It would seem that Tcl really took over a lot of the embedded world, such that companies working on routers and such still use it, or at least did so until recently.

I never loved Tcl, but it was a very clever language for its time, and did wonders to justify the acceptability of doing things in "just" a scripting language.