This isn't exactly what the poster was asking for, but this reminded me of something terribly cool I ran across recently:

http://developer.apple.com/internet/webcontent/XMLHttpRequestExample/example.html

I didn't know you could get JS to fetch data dynamically from the server. Works in at least Firefox and IE.

Anyway, I haven't tried yet, but you might be able to use this to request data from a CGI, although for the original poster's purposes, that's unnecessary. Just have javascript set the value of a hidden field and have the script that handles the submit direct itself to the proper sub based on that value.