One nice trick he uses is to bundle a Tcl interpreter with a MetaKit database into one executable file. This simplifies the task of distributing his Tcl-based software, not to mention that he has access to a small, fast database. The rest of this page is based on a posting of his to the TclHttpd mailing list. Because it is based on a database, such scripted documents can also safely modify themselves while running.
Scripted documents are in production in a range of commercial projects.
As exercise, I just wrapped up the TclHttpd server as scripted document. It does not add functionality to TclHttpd, in fact it does not alter the way TclHttpd works at all - it merely changes the way software is deployed and used.