I am an officer (CTO) of Gateways to CyberSpace[L1 ] and CEO of the Advanced Integrators, LC [L2 ] subsidiary.
Involved in programming since the late 1960's and pre-ARPA digital telecommunications technology at that same time, you'll find traces of my hands all over the current Internet, in some E-Commerce designs, in documentation and standards efforts, and more. Although Tcl and Tcl/Tk are far from the only things I use and specify, I find them extremely convenient, and often the best tool for the job, especially when speed in prototyping is a concern (and when is that not a factor, today).
A starter site at http://tcltk.gtcs.com/ provides housing for a growing set of examples and ponderings that relate to Tcl and Tcl/Tk. Especially popular is the quick comparison of Tcl/Perl/Python and their Tk extensions to BASIC when the personal computer first emerged [L3 ], and a couple of special purpose webbrowsers written exclusively in Tcl/Tk. Sometimes it's difficult to decide between posting there and here on the Tcler's Wiki[L4 ].