[cridal]

If you really want to build a valuable web prototyping app, please make it spit out HTML/CSS. That would be the killer feature! Give me a limited, but functional web site/app that I can then modify/refine, instead of a "picture" of it in whatever else format.

THAT would make me use your product in a hearbeat...

[natrius]

Any HTML or CSS spit out by that app would be unusable without a tremendous engineering effort. Anything can be dragged anywhere. Even if export was only available if you limited yourself to certain functionality and layouts, I'd still be extremely impressed if exported HTML and CSS were worth using.

[misuba]

HTML output would be valuable even if it were as simple as possible and completely unstyled. That's still a tedious step I don't have to do.

[cridal]

For future... host the prototypes on your site, making them instantly accessible to others... maybe also some sort of prototype exchange/marketplace... ideas for expansion are endless, however, first you have to concentrate on the ability to create clean, tight HTML/CSS prototypes