The Tcl Developer Xchange (aka TDX) is a site based on the ArsDigita Community System ACS. It can now be reached via the most Tcl-centric URL the web has to offer:
http://www.tcl.tk/
This site is hosted by ActiveState (and was inherited from Scriptics, Ajuba Solutions, Interwoven).
On 2008-11-07, all the links in this section were broken.
It also contains a resource, which deserves more attention (IMO, JCW):
http://resource.tcl.tk/
Things you will find there are:
Access is open to anyone, adding/maintaining entries requires a simple login so the identity of contributors can be established.
See also Where to store information and programs and places to find Tcl binaries and sources.
" http://www.purl.org/tcl/home/ " is a Purl for "http://tcl.activestate.com/ " (thanks to LV).
Note that thanks to David Welton we the community now have http://www.tcl-tk.net/ and http://www.tcl-tk.org/ too. Both refer to the site above, i.e. "http://tcl.activestate.com/ " But even fancier is http://tcl.tk (or http://www.tcl.tk ) which also go to the Tcl Developer Xchange