[doph]

As a graphics professional who loves node-based workflows, I find the constant re-invention of the wheel pretty painful. With some coordination of this effort, Blender or Natron could be real open-source challengers to Nuke, but starting from scratch seems always to be more enticing.

[themodelplumber]

The reinvention of the wheel with nodes is truly difficult to watch.

There are also very close cousins like Reason and its rack connections, which could contribute some nodes-101-level concepts to most basic graphical node workflows.