Pure JavaScript Graphviz equivalent
Take a look at this pure JavaScript implementation of a .dot canvas renderer:
http://ushiroad.com/jsviz/
The library is not documented -- the author definitely ought to publicize and document it more (I'll contact him to suggest he put it up on github, at the very least).
Update: code has been pushed to github: https://github.com/gyuque/livizjs
Update (14/2/2013): another contender has arisen! anybody interested in the subject should definitely take a look at Viz.js's example page and github repo.
Update (7/16/2020): (seven years later) http://webgraphviz.com/ is also great! :-)
After looking at all the options, I found viz.js (https://github.com/mdaines/viz.js/) based off of jsviz and graphviz.js to actually have an API usable from a webpage, and enough examples to understand.
One could try convert graphviz to javascript, just like it was done for the 'PDF reader' example: https://github.com/kripken/emscripten
After searching far and low I finally found the answer.
The solution was that someone cross compiled Graphviz to Javascript using llvm + emscripten. Here is the link:
http://viz-js.com/
The source can be found at: https://github.com/mdaines/viz.js
And to simply get a webpage up use:
var graphviz_text = ...;
document.body.innerHTML += Viz(graphviz_text, "svg");