Thanks all for the suggestions. Here's a little amplification. All the client machines already have perl installed, so perlscript is an obvious choice. Javascript, which is already built-in to many browsers, is an alternative, but means translating and maintaining some existing perl routinesino Javascript--not ideal. The ActiveState perlscripting engine (and the ActiveState distro) is ruled out for other reasons, as are a local webserver on each client and Tk.
JimE