Development of this module is on hold, until relation is stable at least. I will probably not continue developing it after that, as graphapi seems a far more flexible solution, and may eventually be able to output graphviz graphs anyway. If you feel like taking up the reins of this module leave a note on the issue queue.
Graphviz Noderef displays nodes as a Graphviz graph/map, with NodeReference fields as edges between nodes. This module is being actively developed, and is currrently pre-alpha. Feel free to use it on a production site, but don't be surprised if it breaks.
Usage
Install the module as normal. A new tab will appear on every node, which will include a map with options allowing you to change display settings. Currently, the module only displays node-centric recursive graphs (ie. graphs that start with one node, and work out from there, to a given depth).
The Graphviz Noderef Field sub-module provides a CCK field that shows basically the same map as the graph page.
Dependencies
To run this module, you need Graphviz Filter and CCK.
The module also currently supports bckreferences using the Node Referrer module. More backreferencing modules will be added in the future, check the issue queue for details.