I've got an project management web application where any Project can be the child of zero or one other Project. Our director uses this function to group projects into Service Offerings, and our project managers use this to break projects down into tasks... but from the database's point of view, they're all in the Projects table. So the hierarchy can be arbitrarily deep, although in practice it hasn't gone deeper than 4 levels (yet).
When you're looking at one project's detail page, I want to have some kind of interactive widget that summarizes the whole family into the tightest space possible when you're not interacting with it, but expands gracefully to show as much detail as necessary to navigate around. I think the way file folders are displayed in Windows Explorer is a pretty good metaphor, and I know how to implement that with the YUI TreeView library.
The problem case, I expect, is going to be when I'm looking at one project with dozens of siblings and dozens of children. If I build the whole tree, then expand it enough to show the Project I'm looking at, it's also going to have expanded all my siblings, even though it could hide my children.
Can anyone point me to an interface example that looks like "You are Here. Children exist, click this affordance to show them. You have a parent, click that affordance to show it." ? JavaScript required is ok, Flash would be less popular so it would have to be darn cool. ;)
