I was annoyed because writing graphviz graphs was painful, but thanks to vis.js and emscripten everything can be done in the browser.
This is the first idea of a quick prototyping page for graphs. I'd love to get your feedback and improvement ideas or pull requests, just use the issue tracker in github.
Or just copy the examples from the graphviz Gallery into the text editor and enjoy :). It works good with the simpler examples but has problems with radial layout. Your Browser might hang for a little because everything is rendered on the client.
Have a look at http://dmr.github.io/graphvizeditor.html
This page was made using viz.js (https://github.com/mdaines/viz.js) and knockoutjs (http://knockoutjs.com/) and Behave.js (http://jakiestfu.github.io/Behave.js/), I just combined them.
