We would like to display a node tree graphically - using rectangles for the nodes and lines or arrows to connect them. There are never more than 4 levels of the hierarchy. But it needs to be able to display many-to-one (many parents to one child) relationships. It would also be nice if it provided a slideable or draggable section viewer/navigator to allow quick navigation to a portion of a potentially wide hierarchy.
We were thinking of something like IBM's iLOG Graph Editor, but without the hefty price tag and the additional weighty features we wouldn't need or use.