Lost of people have trouble to understand the concept of Lists in BaseCamp.
The reason is that it's not a List, it's a (content) Filter and only shows you what you put in the filter. If you think about it, it's even an reverse filter and that is in contradiction with the shown hierarchical tree of lists.
It's very confusing to have lists and not been allowed to have multiple items in different lists with the same name, mistakes are easily made, especially when cleaning up items.
Maybe to do it bottom up with filters and not left to right, or call it Content Filter or Content View or Filtered Content.
The Content View is a kind window which only shows you the content for which you have drawn the correct pattern in the damp on the window.
Just a thought and my 10 euro cents :)