- QuickGraph, which didn't seem to have any useful interactive capabilities, and depended on other libraries/code for displaying graphs.
- NodeXL which seemed to be primarily excel based (who does that?), but did have a library component, but didn't seem to be able to even label edges of graphs.
- Netron which seems to have existed once as open source, but is now something else (The website is very unclear about what/if they are selling), there is an older version of the open source code that has lots of components, but it doesn't appear to be geared toward library use.
- Piccolo2D seemed promising, but also seemed to not support labeling edges, and also seemed more oriented towards alternate UI design than simple graph display and manipulation.
P.S. Just in case anyone is wondering, I did consider using Windows Workflow Foundation for our state machines, but they seemed way to heavyweight, and since it sounds like they are rearchitecting the system for version 4.0 (To finally get it right hopefully?). I decided to steer clear.