I've been using Tcl fairly quietly since 1998, but am now breaking cover, since I've been developing a product called Sharpen (http://www.passisoft.com/shqa.html ) to help reduce the costs of the "legacy" Vignette sites that use Tcl. There are still a lot of these out there.
I should be able to announce full details of some significant reference sites in the very near future, lawyers permitting. (I'm waiting for confirmation of brand guidelines etc, which is always a joy.) At the moment all I think I can say is that Sharpen is in use at a major UK financial institution and will soon be in use at a media giant.
I gave a talk on Sharpen at the small but interesting Fifth European Tcl/Tk Users Meeting - the paper is online at http://www.t-ide.com/tcl2005e/6_sharpentcle2005.pdf.gz