I think it would be really cool to be able to write form data to an HTML file, essentially letting users create a page on your site (with strict limitations)

Example:
User fills out form and submits, then on the Thank You page they would be given a link to the HTML document - this could be used for creating Craigslist Templates, etc.

If it was limited to logged in users then the URL of the HTML document could be something like YourWebsite.com/pages/[username].html

I know that if done in the wrong way this could be abused, but it could definitely be put to good use.

I guess this could be done with some clever use of the Integrator, but it would be a good tool to have in QuickMode.