For the project we're working on, we are combining several bits of XML data and using an XSL template to display the HTML. This helps seperate the data from the markup. That way, your PHP or Perl would be responsible for getting the data (in our case, XML from web service calls and XML config files), handling user input, and running the XML/XSL transform. This solution works for us because we can dynamically call different XSL templates depending on the skin we want to display to the user, but the data always coming from the config files and web service calls always stays the same and doesn't care about the markup. The downside here is that this method requires that any database calls or business logic is returning XML. It works great for us, since we're moving all of our logic into a web service layer, and the services always return XML. This might require more architectural work than is necessary in your case, but if the web app is big enough or complicated enough, this method provides some great decoupling.