Insight is a powerful frontend to gdb that uses Tcl/Tk.  It was originally a commercial product written and sold by Cygnus. 

Since Cygnus was purchased by Redhat it's now open source and available here:
http://sources.redhat.com/insight/

This is a sample screenshot from the Redhat site:
[http://sources.redhat.com/insight/screenshots/program-loaded.png]

It uses [incr Tcl] and [[incr Tk]] (included).  It also includes Tcl/Tk 8.4.1.  If someone is interested in updating it...

----
[Category Debugging] [Category Application]