This is a far-off idea, but it would be cool if you had support for various frameworks and could plug into a git repo to map the view data into the templates you're outputting. That way I could continue to use your product for the full lifecycle of development.
Right now I write everything in HTML/CSS by hand and poke around with Firebug to do anything visual with it. I'd love a live-edited version of my view templates with a visual editor like this that generates high-quality code. I would pay a sizable amount of money for such a service.