One interesting job was in allowing a user to create a new record and assign it as part of a hierarchy where not all parts of the parent hierarchy were pre-existing. Normally in QuickBase you'd create the parent, add a child, create the parent, add a child etc. Not much fun and very inefficient.
I've developed an application where the parent nodes can be created while editing the child. In fact in the image shown below the user can add an item to multiple categories at the same time. The user navigates through the hierarchy. The hierarchy is loaded dynamically so that a hierarchy with thousands of nodes doesn't take forever to load mostly un-needed information. The user right clicks on a category to add new child categories. Then the user highlights a selection of categories using standard shift and ctrl click techniques. When the user is finished they click the "Add Selected" button and the original item is added to all the selected categories.
Please contact me if you've a QuickBase project that needs a hierarchy or tree editor.