You will be quite limited without the use of JavaScript to perform this kind of dynamic functionality. HTML alone cannot do this. You can use dynamically generated Javascript, AJAX, Flash or Java.
One possible would be to just use HTML forms and add in an extra button click after the user makes their selection from the first select element. You could create the options for a select element using a CGI script and contain the select element in a form. Position a submit button beside the select element to submit the user's choice back to the server. A handling CGI script could then look at the value and recreate the first select box and the second select box with the appropriate values. -- http://mail.python.org/mailman/listinfo/python-list
