So, I did just that. I whipped up a series of Javascript functions that put the contents of a given form into a text file, call a PHP script on the commandline to process that text file and
then the PHP script sends back a message using another temporary text file. In short, round-trip communication. The current prototype uses calls to "php-cli scriptname.php" as its method for processing forms, but you could easily use Priadoblender-blended scripts instead to do the processing.
What you end up with is a simple way to build "stand-alone"
PHP applications without a web server and using HTML as your widget toolkit and GUI. In addition, the API for processing data is just like it is in a web app: simple name->value pairs. So, someone who is already familiar with building PHP web apps could quickly be up and running using this toolkit. Given the flexibility of this solution, it could become a viable alternative to PHP-GTK (at least for little scripts)
The thing still needs a name and some polish so name suggestions are welcome. I'll be putting it under an open source license on PHPGeek.com when it's done. Contact me if you want to play with a demo.