I want to add where I see value in editors like this (a question that came up in a Google+ comment).
The value is in bundling that experience of live editing together. The editor pane could eventually mature to being an AsciiDoc-aware text editor, perhaps even boosting special key bindings that optimize it for AsciiDoc editing. The pane on the right is a WebKit-based browser, so it's a real preview, on par with desktop editors.
There are two AsiiDoc editors developed by Asiidoctor community members in the early stages of development. Both editors are based on the Asciidoctor Java integration and use JavaFX for the user interface.
To build either one, you'll need JDK 1.7 or better with the JavaFX libraries. I'm really excited about these editors. The two-pane design is the ultimate editing experience because both the AsciiDoc source and a preview of the rendered document are visible at the same time. DoctorFX has the added feature of a raw HTML view as well.
Last, but not least, thanks again for Alex Soto for creating the Asciidoctor Java integration that is fueling this innovation.