Over a year ago I posted an XSL file for prettying up Graphviz diagrams.
I got lots of feedback, and recently I've been fixing various bugs, and I finally got around to adding support for more of the Graphviz node shapes etc.
Here's an example of various node types and colors with ...
I just added a new repository on GitHub containing the tools from my Graphviz / diagram related posts.
The repository can be found at: http://github.com/vidarh/diagram-tools/tree/master
These are the ones included and the appropriate articles: