I got into Tcl long ago when I was developing a test suite. I was immediately drawn to the possibilities of using C to perform the bulk of the 'normal' testing whilst providing hooks in Tcl to implement exceptional scenarios. In the course of this work on a DEC alpha platform I helped fix a couple of bugs to do with porting to LP64 architectures (for which I got a credit in Tcl and the Tk Toolkit book. Thanks John).
Unfortunately Tcl is not a big thing to have on your CV in the UK so I was quite surprised to come across some in my last contract. It all came flooding back and in days I was replacing thousands of lines of C with a few lines of beautiful Tcl!
Oh well, that's over now but I'll keep on trying to help anyone who'll listen to see the light.
The only other scripting language that really interests me is Lua which seems to me to be more suitable for some of the purposes for which Tcl was originally invented but for which it is now looking a bit too fat for.