click on any of the following for the full sized image...
Wilma in action visualising a large clustered graph:
Clusters come in different shapes and sizes:
A screenshot showing the Wilma force controls. Forces can be adjusted interactively and the effects of the changes visible instantly:
A new feature is "planar clusters", where nodes in the cluster are constrained to a plane and the whole cluster is able to rotate to minimise the overall forces: