I need some sort of node-graph editor, that hopefully works on both Mac and other platforms, to generate user created node collections with properties. The graph data will then be used in a data-driven application I’m working on, so kudos if the application can save the graphs in some easy to process format. So far I was using XML with a tree editor, but since the graphs can be cyclic according to the requirements, the tree editor no longer cuts it.
Plugins for other applications would also be ok!
Have a look at Yed (http://www.yworks.com/en/products_yed_about.html), free to use but places a logo on all output.
It comes with Mac OS binaries .. and you might be able to include ($$ required) the graphing engine it is based on into your project.
I’ve used it (with limited success) to document enterprise data-flows..